The dog lung surface-active fraction and phosphatidylcholine constituents were subjected to hydrolysis by Crotalus atrox phospholipase A(2). Relative rates of hydrolysis were: dipalmitoyl glycerophosphorylcholine > phosphatidylcholine isolated from the surface-active fraction > phosphatidylcholine as an integral component of the intact surface-active macromolecular structure. Cholesterol marked...

Batch hydrolysis kinetics of paper birch (Betula papyrifera) xylan and its associated acetyl groups in dilute sulfuric acid have been measured for acid concentrations of between 0.04 and 0.18M and temperatures of between 100 and 170 degrees C. Only 5% of the cellulose was hydrolyzed for up to 85% xylan removal. Rate data were correlated well by a parallel reaction model based on the existence o...

Ribosomes of streptomycin-resistant strains (&r-R) translate genetic messages with fewer errors than ribosomes of streptomycin-sensitive (S&S) strains. I have examined whether the increased level of tRNA discrimination by &r-R ribosomes, relative to Str-S ribosomes, occurs in an initial discrimination step before GTP hydrolysis during enzymatic tRNA binding, or in a second discrimination, or pr...

The hydrolysis of iminohydantoins generates the same tetrahedral intermediate as that obtained in the cyclization of hydantoic acid amides to hydantoins. The ratio of the products of imine hydrolysis under kinetic control is determined by the relative height of the barriers of the breakdown of to amide or to hydantoin. Thus the partitioning of products unequivocally proves which is the rate det...

The phosphate group of the ADP-insensitive phosphoenzyme (E2-P) of sarcoplasmic reticulum Ca2+ -ATPase (SERCA1a) was studied with infrared spectroscopy to understand the high hydrolysis rate of E2-P. By monitoring an autocatalyzed isotope exchange reaction, three stretching vibrations of the transiently bound phosphate group were selectively observed against a background of 50,000 protein vibra...

Freeze-dried systems containing sucrose and organic acids were found to undergo rapid nonenzymatic browning, even at low relative humidities. Addition of protein reduced the rate of browning, especially at low humidities. It was determined that the browning was due to reducing sugars produced by acid-catalyzed hydrolysis of sucrose. This hydrolysis occurred even when water content was well belo...