Free sulfhydryl and disulfide groups of an acid-soluble and acid-precipitable fraction and of isolated plasma membranes were quantified in fresh and stored human platelets. Fresh platelets contained 26.6 X 10 moles of total thiols including hee sulfhydryl and disulfide groups per iO cells. One-third of these thiols were present as disulfides. Acid-soluble thiols accounted for one-tenth of the t...

Two groups of male guinea pigs were exposed to 5 and 10 p.p.m. nitrogen dioxide, 2 hr daily for 35 consecutive days, respectively. The third group, exposed to clean room air, was used as control. Total, free and protein bound sulfhydryl groups were estimated in the cerebral hemisphere cerebellum, midbrain and spinal cord. Significant decrement in total and protein bound sulfhydryl groups and in...

Wherever the point has been examined (e.g. References l-6), pyridoxal phosphate enzymes have been found to require free sulfhydryl groups for activity. The functional role played by these groups, however, has not been clear. In glutamate-oxaloacetate transaminase, which has been studied most extensively, no spectrophotometric or enzymatic evidence for their participation in coenzyme binding was...

The sensitivity of growing bacterial cells to destructive agents or influences is many times that of bacterial spores (Curran, 1952). Some of these agents act on sulfhydryl groups of proteins; on the other hand, sulfhydryl groups belong to the most sensitive groups in proteins and are vital for the function of many enzymes (Barron, 1951). The question may be raised whether the degree of resista...