TABLE 3.

Substrate specificity of pseudoalterin on various substrates

Substrate	Activity (units/mg)a
	Pseudoalterin	Myroilysinb	Pseudolysinb
Casein	0	8541	7061
Elastinorcein	527.9	243.3	91.1
Gelatin	12.0	4.5	5.0
Bovine-insoluble type I collagen fiber	4.9	3.8	0
Gamma globulinc	0	–	–
Furylacryloyl-Gly-Leu-NH2d	0	0	642
Furylacryloyl-Gly-Phe-NH2d	0	0	3,364
Fibrinc	No hydrolysis	Hydrolyzes α, β, and γ	Hydrolyzes α, β, and γ
Oxidized insulin B chain	Gly-8↓Ser-9, Glu-13↓Ala-14, Leu-15↓Tyr-16, Tyr-16↓Leu-17, Leu-17↓Val-18, Cys-19↓Gly-20, Glu-21↓Arg-22, Gly-23↓Phe-24, Phe-24↓Phe-25, Lys-29↓Ala-30	Asp-3↓Gln-4, His-5↓Leu-6, Leu-6↓Cys-7, Ser-9↓His-10, His-10↓Leu-11, Tyr-16↓Leu-17, Phe-25↓Tyr-26, Tyr-26↓Thr-27, Thr-27↓Pro-28, Lys-29↓Ala-30	His-5↓Leu-6, His-10↓Leu-11, Ala-14↓Leu-15, Tyr-16↓Leu-17, Leu-17↓Val-18, Gly-23↓Phe-24, Phe-24↓Phe-25, Phe-25↓Tyr-26, Lys-29↓Ala-30

^a Unless otherwise indicated, the values are specific activities (in units/mg) at 25 °C. The data are the means of three experiments, and the standard deviations were ≤5%.

^b The data on the substrate specificity of myroilysin and pseudolysin are cited from a previous study (13) and the MEROPS Database.

^c Hydrolysis of gamma globulin and fibrin by pseudoalterin was performed at 25 °C, and the results were analyzed by SDS-PAGE (supplemental Fig. S6). – indicates not done.

^d The proteolytic activities with furylacryloyl-Gly-Leu-NH₂ and furylacryloyl-Gly-Phe-NH₂ were measured with Feder's method at 25 °C (42); the data are the values of k_cat/K_m (in m⁻¹ s−1).