Synapsin I phosphorylated by Ca2+, calmodulin-dependent protein kinase II is able to self-degrade.

Phosphorylation of the neurospecific protein synapsin I (SI) by various cellular protein kinases was studied. The analysis of functional properties of phosphosynapsins showed that in the case of PK II-mediated modification of the protein, it becomes capable of self-degradation. The latter process was found to be specific and did not appear to be characteristic of the phosphoforms emerging after the protein modification by PK C or PK A. A possible involvement of the process in the regulation of neurotransmitter secretion is discussed.     

Quantitative dansyl micromethod of amino acid analysis. Study of peptide maps of ribonuclease tryptic hydrolysate

Some variants of the quantitative dansyl method in combination with thin-layer chromatography on polyamide plates have been compared, and principles of its optimization have been demonstrated. Sensitivity of the method is about 10(-11) mole, the error does not exceed 10%. Data are given on the analysis by the dansyl method of peptides of the tryptic hydrolysate of bovine pancreatic ribonuclease after their separation by peptide mapping procedure.     

Metabolic and genetic control of isoenzyme spectrum of alkaline phosphatase inEscherichia coli

Three proteins possessing alkaline phosphatase activity were detected in a fraction of periplasmic material ofEscherichia coli K-10 and its mutants with constitutive synthesis of alkaline phosphatase. They also showed acid phosphatase, pyrophosphatase and ATPase activities. Through the use of phosphatase-negative mutants it was shown that these proteins were the products of a single structural gene and therefore represented alkaline phosphatase isozymes. The numbers of enzyme isoforms and possibly the spectrum of their phosphohydrolase activities were controlled by exogenous orthophosphate and depended on the integrity of regulator genes for alkaline phosphatase.     

Muscle dipeptides--natural inhibitors of lipid peroxidation

The effects of carnosine (beta-alanyl-L-histidine) and anserine (beta-alanyl-1-methyl-L-histidine) on ascorbate-dependent lipid peroxidation in frog skeletal muscle sarcoplasmic reticulum were studied. It was found that the dipeptides (10-50 mM) cause a 25-90% inhibition of ascorbate-dependent lipid peroxidation and decrease the reaction rate and the amount of end products. The nature of lipid peroxidation primary products in the presence of the dipeptides changes which can be evidenced from changes in their spectral properties. Unlike other known natural antioxidants, skeletal muscle dipeptides do not only inhibit lipid peroxidation but also decrease the level of accumulated lipid peroxidation products. Histidine and beta-alanine, similar to imidazole, glycyl-glycine, arginyl-phenyl alanine and alpha-alanyl-D-histidine do not inhibit lipid peroxidation. At the same time, the carnosine stereoisomer D-carnosine which does not exist in nature exhibits a far greater inhibiting effect as compared to its natural counterpart. It is assumed that the skeletal muscle dipeptides carnosine and anserine are highly effective as natural antioxidants.