[Interaction of salts of transition metals with gramicidin S in chloroform]. / Vzaimodeistvie solei nekotorykh perekhodnykh metallov s gramitsidinom S v khloroforme.

Extraction of CuCl2, NiCl2, CoCl2 and MnCl2 from the aqueous phase to the organic gramicidin S containing phase (the phase ratio of 1:1) was studied with the method of molar ratios at constant concentrations of the salts and changing concentrations of the antibiotic. The composition of the forming intracomplex compounds was determined with the equilibrium shift method. It was shown that 2 ions of chlorine and 2 molecules of gramicidin S bound with 1 ion of the metals. The extraction constants were measured. The complex compounds of gramicidin S with copper chloride were the most stable.

[Acidity and solubility of gramicidin S in water]. / Kislotnost' i rastovrimost' gramitsidina S v vode.

The acid-base transformations of the gramicidin S molecule in water were studied. The protonization constants of the antibiotic amino group were calculated by the data of the potentiometric titration and the antibiotic distribution in the system of chloroform-water: K1 1.55 X 10(10), K2 1.38 X 10(6), the logarithm of the distribution coefficient of gramicidin S in the system of chloroform-water (1:1) lg alpha G 4.10. By the same data the constants of water solubility of gramicidin S base (1.02 X 10(7) mol/l), gramicidin S monohydrate (1.06 X 10(-4) mol/l) and gramicidin S dihydrochloride (2.08 X 10(-4) mol/l) were calculated.

[Polyene antibiotics stability, study of the rate of the heterogeneous destruction of the hepataene antibiotic levorin by an "accelerated aging" method and the possibility of predicting the shelf life of levorin]. / Stabil'nost' polienovykh antibiotikov, izuchenie skorosti geterogennoi destrucktsii gepatenovogo antibiotika levorina metodom "uskorennogo stareniia" i vozmozhnost' prognozirovaniia sroka khraneniia levorina.

The data on stability of levorin of various purity levels stored under natural conditions and under conditions of thermic rapid inactivation are presented. When the ratio of oxygen to the antibiotic was 1 mole/1 mole the kinetic inactivation curve was of a multistage character with periods of active destruction and quasistatic state. The use of thermic inactivation as a method of accelerated aging is substantiated. A procedure for calculation of the expiry date of the antibiotic is described.

[Acid-base properties of gramicidin C]. / Kislotno-osnovnye svoistva gramitsidina C.

The acid and basic properties of gramicidin S, a polypeptide antibiotic were studied. Calculation of the protonization constants with the Schwarzenbach method showed that the capacity of the antibiotic amino groups for protonization depended on both the solvent nature and the gramicidin S concentration. No such phenomena were observed in the study on the acid and basic properties of N,N -dimethyldiaminogramicidin. This confirmed the possible effect of the association of the gramicidin S molecules on the protolytic properties of the antibiotic.

[Method of determining the acid-base properties of antibiotics in water-alcohol solutions]. / K metodu opredeleniia kislotno-osnovnykh svoistv antibiotikov v vodno-spirtovykh rastvorakh.

The pH scale of aqueous-alcoholic solutions titrated with aqueous solutions of hydrochloric acid and sodium hydrate was developed. These agents are most frequently used in investigation of the acid and basic transformations of antibiotics. The use of the scale was exemplified with the study of acid and basic properties of gramicidin S containing 2 amino groups in the side chain. Calculation of the constants of protonization of the amino groups of gramicidin S showed their significant differences depending on the solvent nature.