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1.
J Clin Endocrinol Metab ; 84(3): 967-70, 1999 Mar.
Article in English | MEDLINE | ID: mdl-10084580

ABSTRACT

Treatment with recombinant human GH (rhGH), alone or in combination with the anabolic steroid oxandrolone (OX), has been recommended for girls with Turner's syndrome to improve final height. Several cardiovascular risk factors have been described in patients with Turner's syndrome, but the effect of therapy with rhGH and OX on lipoprotein(a) [Lp(a)] has not been investigated. Lp(a) serum levels and apolipoprotein(a) phenotypes were determined in 46 girls with Turners syndrome (aged 6-15 yr) during treatment with different combinations of rhGH and OX for 24-36 months (median, 27 months). Lp(a) serum levels showed little variation during 30 months of treatment in all treatment groups. Lp(a) levels showed no significant change in 25 patients receiving only rhGH and in 21 patients receiving rhGH and OX in combination. Treatment effects were independent of apolipoprotein(a) phenotypes and were not influenced by pubertal status. These data indicate that long term administration of rhGH has no significant impact on serum Lp(a) levels in girls with Turner's syndrome.


Subject(s)
Human Growth Hormone/therapeutic use , Lipoprotein(a)/blood , Turner Syndrome/blood , Turner Syndrome/drug therapy , Adolescent , Apolipoproteins A/blood , Apolipoproteins A/genetics , Child , Drug Combinations , Female , Humans , Oxandrolone/therapeutic use , Phenotype , Puberty/blood , Recombinant Proteins , Time Factors
2.
Am J Dis Child ; 146(5): 582-7, 1992 May.
Article in English | MEDLINE | ID: mdl-1621660

ABSTRACT

Sixty-nine growth hormone-deficient patients were treated for 1 year with somatotropin (recombinant DNA-derived human growth hormone) produced in mouse cells. The growth velocity of the 50 patients (72%) in whom the effectiveness of this growth hormone could be evaluated increased from a mean (+/- SD) of 3.5 +/- 1.1 to 8.7 +/- 1.6. cm/y. An enhanced rate of weight gain was also observed. Bone age was not unduly accelerated. One of 66 patients developed antibodies to recombinant growth hormone, which did not affect the response to therapy. No patient developed antibodies to host cell proteins. An increased insulin response to a standard glucose load, without any change in glucose tolerance, was observed after 1 year of treatment. This authentic sequence human growth hormone preparation produced in mammalian cells is both effective and safe in the treatment of children with growth hormone deficiency.


Subject(s)
Growth Disorders/drug therapy , Growth Hormone/therapeutic use , Adolescent , Child , Child, Preschool , Female , Glucose/metabolism , Growth Disorders/blood , Growth Disorders/metabolism , Growth Hormone/deficiency , Growth Hormone/pharmacology , Humans , Insulin/blood , Male , Recombinant Proteins/pharmacology , Recombinant Proteins/therapeutic use , Thyroid Gland/drug effects , Treatment Outcome
3.
Horm Res ; 37 Suppl 2: 14-21, 1992.
Article in English | MEDLINE | ID: mdl-1490663

ABSTRACT

The effect of a mammalian-cell-derived recombinant human growth hormone (rhGH) on nitrogen and whole-body protein metabolism was assessed in 12 children with complete growth hormone (GH) deficiency. All the patients received single oral doses of 15N-glycine (95 atom % 15N), 20 mg/kg body weight, prior to and following 7 days of treatment with rhGH, 1.7 IU/m2 body surface area (BSA) per day, administered subcutaneously. Prior to rhGH, mean urinary 15N-nitrogen excretion was 42.8 +/- 8% of the administered dose, which fell significantly to 22.8 +/- 7% during rhGH administration (p < 0.0001). Stimulation of protein metabolism by rhGH resulted in a protein net gain rate of 1.1 +/- 0.4 g/kg/day, which was significantly higher than the 0.6 +/- 0.5 g/kg/day rate seen prior to rhGH (p < 0.001). In patients subsequently placed on daily subcutaneous injections of rhGH 1.7 IU/m2 BSA, mean height velocity standard deviation score (HV SDS) for chronological age significantly increased from -3.8 +/- 2.6 to +8.5 +/- 3.1 and +3.3 +/- 2.2, during the 1st and 2nd years of treatment, respectively. However, there was no correlation between the long-term response to rhGH treatment and the short-term changes in nitrogen or protein metabolism in GH-deficient children.


Subject(s)
Child Development/drug effects , Growth Hormone/deficiency , Nitrogen/metabolism , Proteins/metabolism , Adolescent , Alkaline Phosphatase/blood , Body Height/drug effects , Child , Child, Preschool , Drug Administration Schedule , Female , Growth Hormone/administration & dosage , Growth Hormone/therapeutic use , Humans , Insulin-Like Growth Factor I/analysis , Male , Recombinant Proteins , Time Factors
4.
Horm Res ; 37 Suppl 2: 28-36, 1992.
Article in English | MEDLINE | ID: mdl-1490665

ABSTRACT

In five clinical studies performed in Austria, France, the FRG, Italy, Switzerland, the UK and the USA, 304 growth hormone (GH)-deficient children were treated with recombinant human GH (rhGH) of mammalian cell origin. Two hundred and twenty-five patients were previously untreated (naive patients), and 79 were transferred from pituitary hGH after interruption of therapy for at least 6 months (transfer patients). Two treatment protocols, differing in both dose and frequency of injections, were used: (1) a dose of 0.6 IU/kg body weight per week was administered in 3 s.c. injections to 203 patients (178 naive, 25 transfer; group 1); and (2) a dose of 0.45 IU/kg body weight per week was administered in 7 s.c. injections to 101 patients (47 naive, 54 transfer; group 2). After 1 and 2 years of treatment, 143 and 109 naive, and 51 and 46 transfer patients, respectively, were still prepubertal, and their data were analyzed for efficacy. During the 1st year of treatment, both naive and transfer patients on daily injections (group 2) demonstrated better growth than those on 3 injections per week (group 1), with height velocities (HVs) of 10.6 +/- 2.7 cm/year (group 2) versus 8.6 +/- 2.0 cm/year (group 1) for naive patients (p < 0.001), and 9.9 +/- 1.9 cm/year (group 2) versus 7.2 +/- 2.7 cm/year (group 1) for transfer patients (p < 0.001). The corresponding changes in height standard deviation score (delta H SDS) for chronological age (CA) were +1.3 +/- 0.6 (group 2) versus +0.8 +/- 0.5 (group 1) for naive patients (p < 0.01), and +1.1 +/- 0.3 (group 2) versus +0.6 +/- 0.4 (group 1) for transfer patients (p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)


Subject(s)
Child Development/drug effects , Growth Hormone/therapeutic use , Animals , Bone Development/drug effects , Cell Line/metabolism , Child , Female , Growth Disorders/drug therapy , Growth Hormone/biosynthesis , Growth Hormone/deficiency , Humans , Male , Mice , Puberty , Recombinant Proteins , Time Factors
5.
Horm Res ; 37 Suppl 2: 47-55, 1992.
Article in English | MEDLINE | ID: mdl-1490667

ABSTRACT

The development of anti-human growth hormone (anti-hGH) and anti-host-cell protein antibodies to recombinant hGH (rhGH) of mammalian cell origin was determined in 395 children (304 GH deficiency; 91 Turner syndrome) undergoing long-term treatment (up to 54 months) for growth disorders. In all patients, blood samples were obtained prior to and every 2-3 months during treatment, and analyzed at a central laboratory for anti-hGH antibodies by RIA and antibodies to host-cell antigens by ELISA. During the first 24 months of treatment, 9 (3%) of the 304 patients with GH deficiency developed antibodies to rhGH for longer than 3 months. However, persistent antibodies were seen in only 2 patients, both of whom had proven hGH-N gene defects. In the remaining 7 (2%) anti-rhGH-antibody-positive patients, antibody concentrations showed a tendency to increase for 3-12 months, irrespective of the time of onset of measurable concentrations, and declined thereafter. In these patients, binding capacities were between 0.01 and 0.1 mg/l, and binding affinities were between 7 x 10(8) and 8 x 10(9) l/mol. Height velocity was unaffected in these children. None of the 91 patients with Turner syndrome developed persistent anti-hGH antibodies. Further, no child developed antibodies to host-cell antigens during treatment with rhGH of mammalian cell origin.


Subject(s)
Growth Hormone/immunology , Turner Syndrome/drug therapy , Adolescent , Animals , Antibodies/analysis , Antibody Formation , Cell Line/metabolism , Child , Child, Preschool , Enzyme-Linked Immunosorbent Assay , Female , Growth Hormone/biosynthesis , Growth Hormone/deficiency , Growth Hormone/therapeutic use , Humans , Infant , Radioimmunoassay , Recombinant Proteins , Time Factors
6.
Horm Res ; 37 Suppl 2: 5-13, 1992.
Article in English | MEDLINE | ID: mdl-1490668

ABSTRACT

The pharmacokinetics and acute effects of an authentic recombinant DNA-derived human growth hormone (rhGH) produced by genetically engineered mammalian cells were determined in 12 healthy volunteers following intravenous (i.v.), intramuscular (i.m.) and subcutaneous (s.c.) administration of 4 IU (1.3 mg) hGH/m2 body surface area. Following i.v. administration, apparent elimination half-life of rhGH was 18 min. Following i.m. administration, a mean peak serum concentration of 36.9 ng/ml (range 13-61 ng/ml) occurred at 3 h, and following s.c. administration, more sustained but lower serum concentrations occurred, with mean peak concentrations of 16.4 and 16.3 ng/ml at 4 and 6 h (ranges 9.0-27.5 ng/ml and 6.5-35.5 ng/ml at 4 and 6 h, respectively). The mean area under the curves was lower after s.c. (134 +/- 48 ng.h.ml-1) than after i.m. (194 +/- 48 ng.h.ml-1) injections (p < 0.03). Comparable results were obtained for the same dose of rhGH given subcutaneously in concentrations of either 4 IU/ml or 10 IU/ml. Both i.m. and s.c. administrations caused similar increases in free fatty acids at 4 h and insulin-like growth factor I at 24 h. Insulin, C-peptide and blood glucose were almost unchanged during the first 4 h after administration, whereas leukocytes increased significantly (p < 0.0001). Local and systemic tolerance were good, and no adverse reactions were observed. In a GH-deficient child, hGH serum levels between 10 and 20 ng/ml were demonstrated for a period of 8 h after s.c. administration of 0.07 IU rhGH/kg body weight.


Subject(s)
Blood/drug effects , Growth Hormone/pharmacology , Adult , Endocrine Glands/drug effects , Female , Growth Hormone/pharmacokinetics , Humans , Injections, Intramuscular , Injections, Subcutaneous , Male , Recombinant Proteins
7.
Zhonghua Yi Xue Za Zhi (Taipei) ; 47(1): 7-12, 1991 Jan.
Article in English | MEDLINE | ID: mdl-1848467

ABSTRACT

The safety and efficacy of recombinant DNA produced human growth hormone in the treatment of growth failure in prepubertal children with idiopathic or organic deficiency of pituitary GH has been assessed. Five patients entered this clinical trial. They had never been treated with hGH, anabolic steroids or any medicine that affected GH and all of them were healthy without any chronic disease; except patient 1, who took a surgical operation for cerebellar astrocytoma at the age of 3. Each patient was treated with subcutaneous injection of recombinant somatropin (SAIZEN) at a dosage of 0.2 IU/Kg +/- 10% three times per week in the evening for 1 year. Typical catch up growth was observed. The height increased by between 6.3 and 15.1 cm and their mean growth velocity of 3.7 cm/yr prior to therapy increased to 11.1 cm/yr during one year of treatment. The annual change in bone age during the treatment with SAIZEN was 2.0 +/- 0.6 years in four patients, except patient 2 who showed different bone age (right hand 3.5 years, left hand 6.0 years). Anti-hGH antibodies were observed in patient 1, but the binding capacity was low (1:10), and no clinical symptoms or growth attenuation occurred. No side effects or laboratory abnormalities were noted throughout the clinical trial. In conclusion, recombinant somatropin has a growth promoting effect and low immunogenicity, and it is shown to be safe and effective during the first year of therapy in children with GH deficiency.


Subject(s)
Dwarfism, Pituitary/drug therapy , Growth Hormone/deficiency , Body Height/drug effects , Body Weight/drug effects , Child , Female , Growth Hormone/immunology , Growth Hormone/therapeutic use , Humans , Insulin-Like Growth Factor I/analysis , Male , Recombinant Proteins/therapeutic use
8.
J Clin Endocrinol Metab ; 70(5): 1292-8, 1990 May.
Article in English | MEDLINE | ID: mdl-1692331

ABSTRACT

The acid-stable subunit of the GH-dependent large mol wt somatomedin-binding protein (SmBP) was isolated from human plasma Cohn fraction IV by a three-step procedure, and a specific RIA was developed which allowed measurement in unextracted serum. Although in normal human serum most of immunoreactive material was present as the large mol wt complex (150K), considerable amounts of smaller components were found by high performance liquid exclusion chromatography in the 60K, 42K, and 32K range. Normal serum levels were low at birth, rose sharply during the first weeks of life, and showed a moderate peak at puberty. To assess the diagnostic efficacy of SmBP for GH deficiency (GHD), patients previously diagnosed as GH-deficient by conventional criteria (n = 132) were compared to short statured children without GHD (n = 130). Taking the fifth centile as a limit of normality the majority of patients with GHD had subnormal levels, yielding high sensitivity of the test (0.97). In contrast, most of the non-GH-deficient children had SmBP levels within the normal range, resulting in high specificity (0.95) and, consequently, high accuracy (0.96). These results suggest that the large mol wt SmBP is an excellent screening parameter and is highly informative for GHD.


Subject(s)
Carrier Proteins/blood , Dwarfism, Pituitary/blood , Growth Disorders/blood , Growth Hormone/deficiency , Adolescent , Adult , Biomarkers/blood , Carrier Proteins/isolation & purification , Child , Child, Preschool , Chromatography, Gel , Chromatography, High Pressure Liquid , Cross Reactions , Dwarfism, Pituitary/diagnosis , Female , Growth Disorders/diagnosis , Growth Hormone/blood , Growth Hormone/physiology , Humans , Immune Sera/immunology , Infant , Infant, Newborn , Insulin-Like Growth Factor Binding Proteins , Insulin-Like Growth Factor I/analysis , Insulin-Like Growth Factor II/analysis , Male , Radioimmunoassay
9.
Acta Endocrinol (Copenh) ; 121(4): 501-4, 1989 Oct.
Article in English | MEDLINE | ID: mdl-2800924

ABSTRACT

Clinical manifestations of allergy to biosynthetic hGH were not reported in 245 patients treated for one year. A sensitive radioallergosorbent test showed, however, the presence of anti-hGH IgE antibodies in the sera of 13%. All patients with anti-hGH IgE had also elevated concentrations of total serum IgE, similar to atopic persons (2459 +/- 147 micrograms/l, normal 70 +/- 8, 2p less than 0.0001); 83% of all patients who had specific IgE antibodies to hGH had specific antibodies prior to treatment. Administration of hGH did not consistently change concentrations (up to 8 micrograms/l) or affinities (less than 10(7) to 1.3 X 10(9) l/mol) of the specific reagins. Anti-hGH IgE antibodies were related to atopy. Treatment with biosynthetic hGH did not significantly stimulate specific IgE.


Subject(s)
Drug Hypersensitivity/immunology , Growth Hormone/immunology , Immunoglobulin E/analysis , Adolescent , Adult , Child , Growth Hormone/therapeutic use , Humans , Radioallergosorbent Test
10.
Horm Metab Res ; 21(8): 427-30, 1989 Aug.
Article in English | MEDLINE | ID: mdl-2571553

ABSTRACT

Antibodies to GHRH1-44, GHRH1-29, and proinsulin were induced in guinea pigs. GHRH1-44 forms 7 S and 10 S complexes with antibodies. It is a divalent antigen. The sequence 30-44 bound 85% of the antibodies to GHRH1-44 with high affinity (3.8 +/- 0.9 x 10(9) l/mol). The fragment 1-29 bound with low affinity (0.6 +/- 0.3 x 10(9) l/mol) 15% of the antibodies (2p less than 0.001). Antibodies to GHRH1-29 had low affinity towards the native hormone (0.4 +/- 0.2 x 10(9) l/mol) and the region 1-29 (0.3 +/- 0.2 x 10(9) l/mol). Antibodies to proinsulin bound linear C-peptide with lower affinity (0.3 +/- 0.2 x 10(9) l/mol) than the C-peptide loop in proinsulin (3.4 +/- 0.9 x 10(9) l/mol). It is concluded that the conformation of the epitopes on the sequence 1-29, recognized during the immune response, i.e. on the cell membrane, is different from the conformation of GHRH1-29 or GHRH1-44 in aqueous solution.


Subject(s)
Growth Hormone-Releasing Hormone/immunology , Animals , Antibody Formation , Carrier Proteins/immunology , Cell Membrane/immunology , Guinea Pigs , Immunoglobulin G/immunology , Iodine Radioisotopes , Male , Proinsulin/immunology , Protein Conformation
11.
Eur J Pediatr ; 148(7): 591-6, 1989 Jun.
Article in English | MEDLINE | ID: mdl-2663511

ABSTRACT

Following an initial report from Japan in 1987, 15 growth hormone (GH)-deficient patients developed leukaemia during or following GH treatment. Nearly all available pituitary and biosynthetic growth hormones have been used. In 14 of these 15 patients GH treatment was initiated in 1975 or later with doses between 4.5 and 18IU/m2 per week. The therapy period was between 0.17 and 8.0 years. Leukaemia occurred 0.2-11 years after the start of GH treatment. GH affects normally and abnormally growing blood cells in vitro and in animal experiments, but the clinical data in humans do not indicate GH induction of tumour growth. Seven out of the 14 patients under discussion had an additional increased leukaemia risk. Two other patients had been treated only for a very short time. Though no clear evidence of a strikingly augmented leukaemia incidence in GH-treated patients is found worldwide, the available data call for increased attention.


Subject(s)
Growth Hormone/adverse effects , Leukemia/chemically induced , Adolescent , Child , Child, Preschool , Female , Growth Hormone/therapeutic use , Humans , Male
12.
Growth Dev Aging ; 52(4): 193-200, 1988.
Article in English | MEDLINE | ID: mdl-3255726

ABSTRACT

Increased levels of endogenous growth hormone (GH) during childhood and adolescence result in a significant elevation of final height both in humans and in laboratory animals. We investigated the growth promoting effects of the administration of pharmacological doses of human GH (25 to 100 IU/kg/day) in 7 rats with severe intrauterine growth retardation (IUGR) due to artificially induced embryofetal alcohol syndrome (EFAS). Such doses of GH led to a marked growth spurt during the time of administration (14 days) exceeding the expected daily length and weight gain significantly, compared to placebo-treated EFAS litter and healthy controls (P less than 0.01, resp. P less than 0.05). This growth increment persisted in all treated animals throughout the total period of observation (250 days). Three out of the seven animals even showed incremental growth curves of both length and weight that stayed continuously within the +/- 2 standard deviation range of normally growing animals. Thus, it is shown for the first time that also exogenous GH administered temporarily at doses beyond the physiological level results in a significant elevation of final body size.


Subject(s)
Aging/drug effects , Fetal Alcohol Spectrum Disorders/physiopathology , Growth Hormone/pharmacology , Growth/drug effects , Animals , Body Constitution/drug effects , Body Weight/drug effects , Female , Growth Hormone/administration & dosage , Male , Pregnancy , Rats , Rats, Inbred Strains , Weight Gain/drug effects
13.
Horm Metab Res ; 18(12): 854-7, 1986 Dec.
Article in English | MEDLINE | ID: mdl-3817750

ABSTRACT

Guinea pigs were immunized with extracted human growth hormone. Human sera were obtained after treatment with biosynthetic methionyl hGH. The size of hGH-anti hGH antibody complexes was determined from the sedimentation velocity at 100,000 g. At an excess of hGH over antibodies 8 S complexes were uniformly observed in human and guinea pig sera. S values between 11.8 and 15.6 were observed at antibody excess in individual guinea pig sera. Antibodies from humans treated with methionyl hGH formed smaller complexes (7.5 S). One patient with GH-deficiency developed resistance to treatment. Complexes of 12.3 S were formed by his antibodies. HGH sustains the formation of antibody complexes containing more than three IgG molecules (15.6 S). It is discussed that human antibodies of higher diversity may form complexes larger than trimers which initiate the complement cascade.


Subject(s)
Antigen-Antibody Complex/analysis , Growth Hormone/immunology , Immunoglobulin G/metabolism , Animals , Enzyme-Linked Immunosorbent Assay , Growth Hormone/analogs & derivatives , Guinea Pigs , Human Growth Hormone , Humans , In Vitro Techniques , Male , Ultracentrifugation
14.
Klin Padiatr ; 195(5): 342-6, 1983.
Article in German | MEDLINE | ID: mdl-6632713

ABSTRACT

Individual observations lead to the realisation that during endoscopy children may develop such a degree of seemingly unexplainable anxiety that the performance of the examination is considerably prejudiced. We therefore examined 39 children systematically, evaluating them according to fearsome products of their imagination on the one hand and real or warranted anxiety on the other. Adjusted to age the children were tested using drawings, projectional tests and role-playing in addition to interviewing, sometimes of their parents as well. The most prominent expressions of anxiety in conjunction with endoscopy were fear of suffocation; fear of damage to internal organs and, in girls, fear of lesions to a "baby inside". In adolescents problems with prudery became evident. On the basis of our experience we developed a systematic model of psychological preparation for endoscopic examinations.


Subject(s)
Endoscopy/psychology , Proctoscopy/psychology , Adolescent , Age Factors , Anxiety , Child , Child, Preschool , Female , Gastroscopy/psychology , Humans , Interview, Psychological , Male , Shame
15.
Science ; 212(4497): 873, 1981 May 22.
Article in English | MEDLINE | ID: mdl-17830170
16.
Dtsch Med Wochenschr ; 105(31): 1086-9, 1980 Aug 01.
Article in German | MEDLINE | ID: mdl-7428623

ABSTRACT

High doses of dexamethasone (Fortecortin) for the prophylaxis of cerebral oedema were administered to 19 children aged 3 to 14 years because of head injury of varying degrees of severity. In order to assess possible suppression of the hypothalamic-pituitary-adrenocortical activity an insulin tolerance test and an intravenous tetracosactid (Synacthen) test was performed 1 to 26 weeks after the last dexamethasone dose. There was no evidence from the insulin tolerance test of inadequate cortisol excretion. After intravenous Synacthen injection satisfactory serum cortisol increase was found. However, from this test there was evidence of a lesser increase of serum cortisol depending on the time elapsed since cessation of dexamethasone. Investigation of circadian cortisol values showed 7 cases with subnormal serum cortisol at 18 o'clock independent of the time elapsed. The hypothalamic-pituitary-adrenocortical axis was functioning again during induced stress 7 days after withdrawal of dexamethasone. Subsequent stress situations do not require treatment with corticoids.


Subject(s)
Dexamethasone/pharmacology , Hypothalamo-Hypophyseal System/drug effects , Pituitary-Adrenal System/drug effects , Adolescent , Brain Edema/prevention & control , Brain Injuries/drug therapy , Child , Child, Preschool , Dexamethasone/therapeutic use , Humans , Hydrocortisone/blood , Time Factors
17.
Klin Padiatr ; 192(4): 351-7, 1980 Jul.
Article in German | MEDLINE | ID: mdl-7192771

ABSTRACT

28 newborn infants, only 3 of which were female, were treated for early-onset streptococcal septicaemia in the years 1970-1978 at the University Children's Hospital, Freiburg. Overall mortality was 60%, that for premature infants 80%. Almost all infants who died developed D.i.C. 60% had X-ray findings consistent with HMD, even among the mature newborns. 90% showed white blood-cell count changes such as Leucocytopenia, Granulocytopenia, rise in percentage of immature granulocytes, Thrombocytopenia. With the help of these signs and using Gram-stain on stomach aspirates early diagnosis and differentiation from HMD seems feasible.


Subject(s)
Infant, Newborn, Diseases/diagnosis , Streptococcal Infections/diagnosis , Diagnosis, Differential , Disseminated Intravascular Coagulation/etiology , Female , Humans , Hyaline Membrane Disease/diagnosis , Infant, Newborn , Infant, Premature , Infant, Premature, Diseases/diagnosis , Leukocyte Count , Male , Sepsis/diagnosis , Sepsis/microbiology , Sepsis/mortality , Streptococcal Infections/mortality
18.
Eur J Biochem ; 65(1): 285-91, 1976 May 17.
Article in English | MEDLINE | ID: mdl-1278182

ABSTRACT

Activity can be induced in potentially active rabbit skeletal muscle phosphorylase monomers covalently bound to Sepharose by noncovalent interaction with soluble subunits carrying inactive pyridoxal 5'-phosphate analogs or even salicyladlehyde. These analogs are themselves incapable of reconstituting active holophorphorylase from apophosphorylase. Phosphorylases with one intrinsically inactive and one potentially active subunit have about one half of the activity of the native phosphorylase dimer. The usefulness of this technique for subunit complementation was demonstrated by forming hybrid phosphorylases with inactive Sepharose-bound rabbit skeletal muscle subunits containing pyridoxal 5'-phosphate monomethylester and soluble activatable frog muscle and rabbit liver phosphorylase monomers. The inactive Sepharose-bound subunit induced in each case activity in the soluble subunit. But whereas the inactive rabbit muscle phosphorylase subunit even transmitted its characteristic temperature dependence of the rate of the reaction to the frog muscle subunit, it could not propagate its control properties to the liver enzyme. Differences of hybrid phosphorylases are related to immunological and amino acid divergencies among the component enzymes.


Subject(s)
Liver/enzymology , Muscles/enzymology , Phosphorylases , Animals , Macromolecular Substances , Organ Specificity , Phosphorylases/metabolism , Protein Binding , Pyridoxal Phosphate/pharmacology , Rabbits , Rats , Species Specificity , Temperature
20.
Proc Natl Acad Sci U S A ; 69(8): 2278-82, 1972 Aug.
Article in English | MEDLINE | ID: mdl-4506097

ABSTRACT

Phospho-dephosphohybrids of rabbit skeletal muscle phosphorylase (EC 2.4.1.1; alpha-1,4-glucan: orthophosphate glucosyl transferase) have been prepared and stabilized by attachment to Sepharose activated by cyanogen bromide. They can be distinguished from phosphorylase a by their sensitivity to inhibition by glucose-6-phosphate and activation by adenosine 5'-monophosphate. Stable hybrids have also been formed between phosphorylase subunits containing the active cofactor pyridoxal-phosphate and inactive analogs (pyridoxalphosphate monomethylester or the corresponding reduced compounds). After complete dissociation to monomers, the Sepharose-bound phosphorylase had a residual activity of less than 3% of that of the original matrix-bound dimeric enzyme. The hybrid enzyme is composed of a potentially active subunit containing pyridoxal-phosphate and an intrinsically inactive subunit carrying the analog, and it had half the activity of the original dimeric enzyme. Thus, the interaction of the inactive subunit with matrix-bound phosphorylase monomers elicited activity in the monomers.


Subject(s)
Glucosyltransferases/analysis , Muscles/enzymology , Adenosine Monophosphate/pharmacology , Animals , Cyanogen Bromide , Enzyme Activation/drug effects , Glucosephosphates/pharmacology , Glucosyltransferases/antagonists & inhibitors , Glucosyltransferases/isolation & purification , Glycogen , Ion Exchange Resins , Kinetics , Methods , Pyridoxal Phosphate , Rabbits
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