Radiochemical determination of a unique sequence around the reactive serine residue of a di-isopropyl phosphorofluoridate-sensitive plant carboxypeptidase and a yeast peptidase |
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| Authors: | D C Shaw and J R E Wells |
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| Institution: | Department of Biochemistry, John Curtin School of Medical Research, Australian National University, Canberra, A.C.T., Australia, and Department of Biochemistry, University of Adelaide, Adelaide, S. Austral. 5001, Australia |
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| Abstract: | Phaseolain, a carboxypeptidase from French-bean leaves, and a partially purified peptidase from baker's yeast are inhibited by reaction with di-isopropyl phosphorofluoridate. Radioactive di-isopropyl (32)P]phosphorofluoridate was used to show that the site of reaction is a unique serine residue and that the sequence of amino acids adjacent to the reactive serine is Glu-Ser-Tyr. This sequence is different from those of other ;serine' enzymes previously reported and, for phaseolain, represents an unequivocal example of a ;serine' carboxypeptidase. |
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