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S Fish

Publications and source records attributed to S Fish.

41 records · Page 3Linked to original sources
PubMed1980

Are carboxylations involving biotin concerted or nonconcerted?

Transcarboxylase and propionyl-CoA carboxylase catalyze the elimination of HF from beta-fluoropropionyl-CoA to form acrylyl-CoA. No carboxylation products of fluoropropionyl-CoA could be detected. The elimination proceeds at approximately the same rate as the normal carboxylation reactions. With propionyl-CoA carboxylase, ATP was required (HCO3- was also present) and was hydrolyzed to ADP and Pi. The rate of ADP formation was equal to that of acrylyl-CoA formation. A previous report (Stubbe, J. A., and Abeles, R. H. (1977) J. Biol. Chem. 252, 8338--8340) that acrylyl-CoA formation is faster than ADP formation is in error. With transcarboxylase, oxalacetate was required for acrylyl-CoA formation, and pyruvate was produced. The rate of pyruvate formation was equal to that of acrylyl-CoA formation. We conclude that the ability of the enzyme to catalyze the elimination of HF from beta-fluoropropionyl-CoA indicates that the enzyme can catalyze the abstraction of the substrate alpha-proton without concomitant carboxylation of the substrate. We also conclude that the normal catalytic reaction, therefore, probably involves a carbanion intermediate and does not proceed through a concerted process as has frequently been proposed.

Acyl Coenzyme A↗
PubMedDate not supplied

Resuscitation fluid for a patient with head injury and hypovolemic shock.

The resuscitation of a patient with severe closed head injury and hypovolemic shock is a commonly encountered clinical scenario. The optimal resuscitation formula remains controversial. Aggressive use of crystalloid solutions may worsen brain injury. Early use of mannitol or hypertonic agents may worsen hemorrhage and shock. The optimal approach to the resuscitation of a patient with head trauma and hypovolemic shock is reviewed and discussed. Recent experimental evidence suggests that the early inclusion of an agent such as mannitol in the resuscitation formula may be appropriate despite the evidence of shock. However, the controversy remains unresolved.

Animals↗
PubMedDate not supplied

Development of GM-CSF antagonist peptides.

Granulocyte/macrophage colony stimulating factor (GM-CSF) is both a hematopoietic growth factor and a cytokine implicated in inflammatory disease. The development of GM-CSF antagonist peptides corresponding to the GM-CSF native sequence should allow their modification into higher affinity analogs, but this is hampered by the low affinity of linear peptides. To adequately evaluate such low affinity peptides, the use of several independent assays should allow specific versus nonspecific inhibitors to be distinguished. In this study, inhibition of GM-CSF-dependent cell growth, inhibition of GM-CSF binding and immunologic cross-reactivity between GM-CSF-derived peptides and native protein by neutralizing antibodies have been used to evaluate peptide analogs with potential bioactivity. The GM-CSF sequence was divided into 6 peptides ranging in size from 15-24 amino acids. Antisera were raised to these peptides in mice and assayed for immunologic cross-reactivity. 4/6 anti-peptide antisera bound GM-CSF on ELISA and 3/6 on immunoprecipitation. Antisera to two of the peptides (corresponding to residues 17-31 and 96-112) inhibited GM-CSF-dependent cellular proliferation in two cell lines, with one peptide derived from residues 17-31 demonstrating inhibition of GM-CSF binding and direct biological inhibitory activity. A peptide that did not elicit native GM-CSF reactive antibodies, corresponding to residues 54-78, was recognized by two neutralizing monoclonal antibodies. It exhibited inhibition of GM-CSF binding and direct biological antagonist activity. These studies implicate two sites in mediating GM-CSF biological activity, and indicate that biological antagonists can be developed based on these sites.

Amino Acid Sequence↗