[Dispute on the source of enzymes' catalytic power].

The source of enzymes' unusual catalytic power is still a controversial problem. Experimental documentation of enzymatic ability to use their natural dynamic motions in catalytic processes did not end the dispute on the origin of the energy necessary for catalytic work. Thus, it seems that resolution of this problem will only follow given an increase in computer power, such that ab initio simulations of the entire, large protein or ribonucleic acid molecule, engaged in a catalytic process, will be possible.

Further studies on the role of phospholipids in determining the characteristics of mitochondrial binding sites for type I hexokinase.

Previous work has indicated that two types (A and B) of binding sites for hexokinase exist, but in different proportions, on brain mitochondria from various species. Hexokinase is readily solubilized from Type A sites by glucose 6-phosphate (Glc-6-P), while hexokinase bound to Type B sites remains bound even in the presence of Glc-6-P. Type A:Type B ratios are approximately 90:10, 60:40, 40:60, and 20:80 for brain mitochondria from rat, rabbit, bovine and human brain, respectively.

Activity of glycogen depolymerizing enzymes in extracts from brain tumor tissue (anaplastic astrocytoma and glioblastoma multiforme).

An approximately threefold increase in glycogenolytic activity of the neutral alpha-1,4-glucosidase and a twofold increase in the same activity of the acid isoform have been found in extracts of anaplastic astrocytoma and glioblastoma multiforme tumors of brain tissue. "Maltase activity" of the respective enzymes increased by 60-80% in both kinds of tumor extracts. However a significant decrease in a-amylase and almost complete disappearance of phosphorylase activities have also been found in both kinds of tumors.

Effect of ligand-induced conformational changes on the reactivity of specific sulfhydryl residues in rat brain hexokinase.

Rat brain hexokinase (ATP:D-hexose 6-phosphotransferase, EC 2.7.1.

[Properties of alpha-1,4 leads to -glucosyltransferase from the muscles and blood serum of horses].

Alpha-1,4 leads to 1,4-glucosyltransferase preparations from horse muscles and serum were studied. The enzyme proteins from both tissues are very similar. Both proteins have a molecular weight of 240 000 and consist of four subunits of 60 000 daltons each.