Enzymic activities of the smooth body-wall muscle of the onychophoran Peripatopsis mosleyi [proceedings].

Discussion From the standpoint of attempting to elucidate the mechanisms whereby pyruvate kinase activity might be regulated in vivo, the results obtained to date, and summarized above, are largely inconclusive. Whereas the enzyme in vitro has been shown to be inhibited by ATP, limiting Mg2+, creatine phosphate, etc., the inhibition is probably insufficient in magnitude to account per se for the presumed flux through pyruvate kinase that occurs in vivo. It is concluded that skeletal-muscle pyruvate kinase is probably severely inhibited at concentrations of substrates and effectors in vivo, and this is consistent with the results of previous studies.