[Effect of the methods of sterilization on the quality of nutrient media and on the level of antibiotic production]. / Vliianie sposobov sterilizatsii na kachestvo pitatel'nykh sred i na uroven' obrazovaniia antibiotikov.

It was shown that conditions for heat sterilization of nutrient media for biosynthesis of antibiotics had an impact on their biochemical composition and activity of a fermentation broth in production of penicillin and erythromycin. The temperature of 120 degrees C and the time of 25 minutes proved to be optimal for sterilization of the media in regard to both preservation of their biochemical composition and providing of the maximum antibiotic productivity on the one hand and maintenance of the sterility during the fermentation process on the other hand.

[Method for developing a controlled process. Study of the possible regulation of rifamycin B biosynthesis]. / Metod razrabotki upravliaemogo protsessa. Issledovanie vozmozhnosti reguliatsii biosinteza rifamitsina B.

A procedure for developing a controlled process for biosynthesis of secondary metabolites is described with reference to rifamycin B as an example. The response of the antibiotic producing culture to changed concentrations of the main nutrients in the initial medium was determined. Mathematical processing of the experimental findings with design of the experiment resulted in defining nutrients such as ammonium sulfate and cornsteep liquor useful for further development of the controlled process.

[A method for developing a controlled process. Development and execution of a program supplying culture medium components for rifamycin B biosynthesis]. / Metod razrabotki upravliaemogo protsessa. Raschet i realizatsiia programmy podpitok komponentami sredy pri biosinteze rifamitsina B.

The study provided data on the rate of consumption of the main nutrients by the rifamycin-producing culture in relation to their content in the initial medium. A program for feeding ammonium sulfate and cornsteep liquor and joint control of both the nutrients was developed and tested. The results of the testing confirmed the practicable precision of the feeding. The control of cornsteep liquor and ammonium sulfate concentrations with the program allowed to increase the yield of rifamycin B by 15 and 20%, respectively. The joint control increased the level of the required product by 25%.

[Effect of partial pressure of solute oxygen on the intensity of respiration of cultures of antibiotic producers]. / Vliianie partsial'nogo davleniia rastvorennogo kisloroda na intensivnost' dykhaniia kul'tur-produtsentov antibiotikov.

It was shown possible to use feeding of hydrogen peroxide as a method for investigating the impact of dissolved oxygen concentrations on growth and development of microorganisms. The influence of pO2 on the respiration intensity was studied in penicillin- and erythromycin-producing cultures and it was found that dependence of the respiration intensity on pO2 had the form of a curve with saturation, at pO2 equal to zero the value of the culture respiration intensity being different from zero. A mathematical model accounting for the presence in the fermentation broth of microbial agglomerates with the average size depending on the agitation conditions is proposed for describing the relationships.

[Conformational isomerization of lactate dehydrogenase complexes formed by pyruvate and coenzyme analogs]. / O konformatsionnykh perestroikakh kompleksov laktatdegidrogena3y, obrazovannykh piruvatom i analogami kofermenta.

The kinetics of LDH-catalyzed reduction of pyruvate involving APADH were studied. It was shown that under conditions of a single turnover reaction the first order rate constant is equal to 37+/-4 sec-1. The reaction rate (vo) did not change when a deutero-coenzyme was used. The relationship between vo and pyruvate concentration is hyperbolic. It is concluded that isomerization of the ternary LDH-APADH-pyruvate complex limits the reaction rate. The spectral properties and the kinetics of formation and dissociation of abortive LDH complexes with pyruvate and NAD analogs (APAD and PAAD) were studied. The participation of the carboxamide group of NAD in conformational isomerization of the LDH-NADH-pyruvate and LDH-NAD-pyruvate complexes was studied.

[Effect on some pyridine derivatives on the activity of heart NAD glycohydrolase]. / Vliianie nekotorykh proisvodnykh piridina na aktivnost'NAD-glikogidrolazy iz serdechnoi myshtsy.

Effect of some 3- and 4-substituted pyridines on enzymatic hydrolysis of NAD by rabbit heart muscle NAD-glycohydrolase has been studied. It is shown that some 4-substituted derivatives in contrast with 3-substituted ones produce an inhibitory effect on the enzyme activity. A new efficient inhibitor of rabbit heart muscle NAD-glycohydrolase (I50 = 10(-3) M)--N1-(2-lactyl)-N2-(isonicotinoy)hydrazine, inducing uncompetitive inhibition of hydrolysis of NAD is found. The mechanism of the inhibitory effect of N1-(2-lactyl)-N2-(isonicotinoyl)hydrazine was investigated and the rate equation for enzymatic hydrolysis of NAD in the presence of inhibitor is calculated. It is suggested, that the inhibitory effect of N1-(2-lactyl)-N2-(isonicotinoyl)hydrazine is due to the formation of triple inactive complex inhibitor-enzyme-adenosinediphosphateribose.

[The interaction of pyridine-adenine-dinucleotides containing a hydrazide group with swine muscle lactate dehydrogenase]. / Vzaimodeistvie piridin-adenin-dinukleotidov, soderzhashchikh gidrazidnuiu gruppu, s laktatdegidrogenazoi myshts svin'i

Hydrazide group of 4-substituted NAD analogues is shown to interact with functional groups of substrate-binding site in double complexes with pig muscle lactate dehydrogenase (isoenzyme M4). The lactic acid residue, which is structurally incorporated into NAD analogue, improves slightly the binding of dinucleotide, while 2,2,6,6-tetramethylpiperidine-1-oxyl residue considerably decreases the firmless of binding. The comparison of the inhibitory ability of oxamate, incotinic acid hydraxide and their spin-labelled derivatives indicates the restricted and stiff sizes of a substrate-binding site.

[Formation of adducts of pyridine nucleotides in the active center of swine lactate dehydrogenase (isoenzyme M4)]. / Obrazovanie adduktov piridinovykh nukleotidov v aktivnom tsentre laktatdegidrogenazy svin'i (izoferment M4)

Isozyme M4 of pig lactate dehydrogenase (LDH-M4) catalyzes reaction of NAD-adduct formation with a nucleophylic agent that is perhaps OH--ion. The T 1/2 of the reaction is 10-30 sec at concentration NAD 2,0-10(-3) M, LDH-M4 50 gamma/ml at pH greater than 8. Initial velocity and limit of the reaction increase at high LDH-M4, NAD and OH--ion concentrations. Pyridine-3-aldehyde and 3-acetyl pyridine analogs of NAD forms fluorescent adducts too, but at OH--ion concentration approximately 0,01 of that in the case of NAD reaction. Isoelectrical point of LDH-M4 determined by isoelectrofocusing method is 8,65 +/- 0,04 pH unit.