Completeness in structural genomics.

Structural genomics has the goal of obtaining useful, three-dimensional models of all proteins by a combination of experimental structure determination and comparative model building. We evaluate different strategies for optimizing information return on effort. The strategy that maximizes structural coverage requires about seven times fewer structure determinations compared with the strategy in which targets are selected at random. With a choice of reasonable model quality and the goal of 90% coverage, we extrapolate the estimate of the total effort of structural genomics. It would take approximately 16,000 carefully selected structure determinations to construct useful atomic models for the vast majority of all proteins. In practice, unless there is global coordination of target selection, the total effort will likely increase by a factor of three. The task can be accomplished within a decade provided that selection of targets is highly coordinated and significant funding is available.

From fold to function.

A number of recent advances have been made in deriving function information from protein structure. A fold relationship to an already characterized protein will often allow general information about function to be deduced. More detailed information can be obtained using sequence relationships to already studied proteins. Methods of deducing function directly from structure, without the use of evolutionary relationships, are developing rapidly. All such methods may be used with models of protein structure, rather than with experimentally determined ones, but model accuracy imposes limitations. The rapid expansion of the structural genomics field has created a new urgency for improved methods of structure-based annotation of function.

[Follicular splenic lymphoid hyperplasia associated with EBV infection].

Massive splenomegaly is defined as a spleen weighing about 10 times normal weight. We describe a 36-year-old man who had huge splenomegaly and secondary pancytopenia simulating malignant lymphoma for about 3 months. Splenectomy was necessary because of the suspicion of hematologic malignancy, especially isolated lymphoma of the spleen, and pain and mechanical abdominal disturbances. On operation, the spleen was 25 cm long and weighted 250 g. There was florid, reactive follicular lymphoid hyperplasia. Immunohistochemical staining with CD-20(L26), CD-45Ro(UCHL), bcl-2 oncoprotein (Dakopatts), EBV (anti-EBV mol weight 60 KD, Dakopatts) was consistent with reaction to EBV infection and not with follicular lymphoma. Lack of PCR amplification using DNA extracted from paraffin-embedded splenic tissue indicated absence of a monoclonal B cell population carrying rearranged immunoglobulin genes. The lymphocytic population was proven polyclonal by the negative results of PCR for the bcl-2 gene rearrangement. EBV seroconversion from high titer antibodies of anti-EBV-VCA-IgM to negative, and from negative EBNA to positive was consistent with an apparent primary EBV infection. We have not found on computerized search a previous report of reactive follicular splenic hyperplasia to EBV infection causing huge splenomegaly, with or without EBV-induced infectious mononucleosis.

[The dynamics of aminotransferase activity in the blood plasma as a reflection of the characteristics of the pathological process in patients with craniocerebral trauma]. / Dinamika aktivnosti aminotransferaz v plazme krovi kak otrazhenie osobennostei patologicheskogo protsessa u bol'nykh s cherepno-mozgovoi travmoi.

The activity of alanin-aminotransferase (ALT) and aspartate-aminotransferase (AST) was measured in blood plasma of 103 patients with brain trauma. Sex-related differences were found. One day after the trauma ALT and AST activity rose significantly both in men and women with brain concussion, in males with mild and moderate brain contusion. In severe brain contusion the enzymes activity did not change. Eight days after the trauma AST activity significantly lowered in patients with brain concussion. No changes in aminotransferases activity one day after severe brain contusion evidence for biochemical maladaptation.

Ectopic medullary hematopoiesis as a cause of ascites in agnogenic myeloid metaplasia. Case report and review of the literature.

We report an unusual case of a 44-year-old female patient with 'malignant' ascites caused by ectopic foci of extramedullary hematopoiesis in the course of agnogenic myeloid metaplasia. The patient had suffered also from severe Coombs-positive acquired hemolytic anemia and had been splenectomized. Two years after splenectomy, ascites caused by peritoneal implants of hematopoietic tissue appeared. The ascites responded promptly to treatment with busulfan and hydroxyurea. The clinical picture, treatment and a review of the literature concerning the mechanisms of this uncommon evolution are discussed.

Peripartum cardiomyopathy.

A 26-year-old woman developed severe postpartum cardiomyopathy in early puerperium. Ligation of the inferior vena cava prevented recurrent pulmonary embolism but did not affect her hemodynamic condition, which deteriorated constantly. During continuous hemodynamic monitoring only vigorous volume replacement with an increase of the left ventricular filling pressure to 32 mm Hg improved cardiac output significantly. The presence of a high titer of antiactin antibodies 9 months after the delivery supports the theory that the peripartum cardiomyopathy was of autoimmune etiology.

Arrangement and conformations of substrates at the active site of pyruvate kinase from model building studies based on magnetic resonance data.

Seventeen distances from two paramagnetic reference points, as determined by nuclear relaxation studies of six active complexes of rabbit muscle pyruvate kinase, have been used to construct molecular models of two composite enzyme complexes. In the model of the hypothetical pyruvate kinase-M(I)-M(II)-ATP-Cr(III)-P-enolpyruvate complex, overlap of the transferred phosphoryl groups of the two substrates, which is required to explain the observed competition, is incomplete, allowing greater than or equal to 1 A for the transition state to form. In the active enzyme-M(I)-M(II)-ATP-Cr(III)-pyruvate complex, the gamma-phosphoryl phosphorus of ATP is in molecular contact (3.0 +/- 0.5 A) with the carbonyl oxygen of pyruvate, consistent with direct phosphoryl transfer, indicating no need for intermediate phosphorylation of the enzyme. The enzyme-bound divalent cation, which forms second sphere complexes with the phosphoryl groups of P-enolpyruvate and ATP, may activate the transferred phosphoryl group indirectly, through a water ligand. By analogy with the position of Cr(III), a second divalent cation may participate more directly by coordination of the triphosphate chain of ATP.

Magnetic resonance studies of the interaction of Co2+ and phosphoenolpyruvate with pyruvate kinase.

Co2+, which activates rabbit muscle pyruvate kinase, competes with Mn2+ for the active site of the enzyme with a KD of 46 muM. Co2+ binds to phosphoenolpyruvate with a KD of 4.1 mM. The structures of the binary Co2+/P-enolpyruvate, and quaternary pyruvate kinase/Co2+/K+/P-enolpyruvate complexes were studied using EPR and the effects of Co2+ on the longitudinal (T1) and transverse (T2) relaxation times of the protons of water and P-enolpyruvate and the phosphorus of P-enolpyruvate. The EPR spectra of all complexes at 6 K, disappear above 40 K and reveal principal g values between 2 and 7 indicating high spin Co2+. For free Co2+ and for the binary Co2+/P-enolpyruvate complex, the T1 of water protons was independent of frequency in the range 8, 15, 24.3, 100, and 220 MHz. Assuming coordination numbers (q) of 6 and 5 for free Co2+ and Co2+/P-enolpyruvate, respectively, correlation times (tauc) of 1.3 times 10(-13) and 1.7 times 10(-13) s, were calculated. The distances from Co2+ and phosphorus and to the cis and trans protons in the binary Co2+/P-enolpyruvate complex calculated from their T1 values were 2.7 A, 4.1 A, AND 5.3 A, respectively, indicating an inner sphere phosphoryl complex. Consistent with direct phosphoryl coordination, a large Co2+ to phosphorus hyperfine contact coupling constant (A/h) of 5 times 10(5) Hz was determined by the frequency dependence of the T2 of phosphorus at 25.1, 40.5, and 101.5 MHz. For both enzyme complexes, the dipolar correlation time tauc was 2 times 10(-12) s and the number of rapidly exchanging water ligands (q) was 0.6 as determined from the frequency dependence of the T1 of water protons. In the quaternary enzyme/Co2+/K+/P-enolyruvate complex this tauc value was consistent with the frequency dependence of the T1 of the phosphorus of enzyme-bound P-enolpyruvate at 25.1 and 40.5 MHz. Distances from enzyme-bound C02+ to the phosphorus and protons of P-enolpyruvate, from their T1 values, were 5.0 A and 8 to 10 A, respectively, indicating a predominantly (greater than or equal to 98%) second spere complex and less than 2% inner sphere complex. Consistent with a second sphere complex on the enzyme, an A/h value of less than 10(3) Hz was determined from the frequency dependence of the T2 of phosphorus. In all complexes the exchange reates were found to be faster than the paramagnetic relaxation rates and the hyperfine contact interaction was found to be small compared to the dipolar interaction. The results thus indicate that the interaction of C02+ with P-enolpyruvate is greatly decreased upon binding to the active site of pyruvate kinase.