TABLE 1.

Substrate specificities of A. oryzae native carboxypeptidase I at pH 4 and of P. janthinellum carboxypeptidase at pH 4.1, as determined with Z-Ala-X substrates^a

Substrate	A. oryzae carboxypeptidase I			P. janthinellum carboxypeptidase kcat/Km (min−1 mM−1)b
	Km (mM)	kcat (min−1)	kcat/Km (min−1 mM−1)
Z-Ala-Ile	0.11	2,500	22,780	340
Z-Ala-Glu	0.10	3,340	33,410	NDc
Z-Ala-Lys	0.12	3,340	27,840	2,900
Z-Ala-Arg	0.11	2,820	25,620	3,400
Z-Ala-Asp	0.27	2,820	10,440	190
Z-Ala-Asn	0.09	1,980	22,040	230
Z-Ala-Gly	0.92	580	630	4
Z-Ala-Phe	0.24	1,770	7,400	1,600
Z-Ala-Tyr	0.09	1,830	20,330	ND
Z-Glu-Tyr	0.11	490	4,450	ND

^aA typical error in K_m and k_cat determinations did not exceed 11%. 

^bData from reference 2. 

^cND, not determined.