The Effect of Added Sodium or Potassium Chloride upon the α-Chymotrypsin Catalyzed Hydrolysis of Chloroacetyl-L-tyrosinamide in Aqueous Solutions at 25° and pH 7.75¹

Use of the pH-Stat in Kinetic Studies of Reactions Whose Products Are Capable of Functioning as Buffers*

“…The independence of values of fc0 and dependence of values of K0 of a-V-acetyl-L-tyrosinhydroxamide upon the concentration of sodium chloride is exactly the opposite of that observed by Shine and Niemann (1955) for a-V-chloroacetyl-L-tyrosinamide and sodium chloride, by Bernhard and Niemann (1957) for a-V-acetyl-L-tyrosinamide and sodium or potassium phosphate, and by Kerr and Niemann (1958) for a-V-nicotinyl-L-tyrosinhydrazide and tris(hydroxymethyl)aminomethane hydrochloride, where in all cases K0 remained invariant and /c0 increased with increasing concentration of salt. With the observation of Martin and Niemann (1958) that both K0 and k0 for methyl hippurate and acetyl-L-valine methyl ester varied with the concentration of sodium or potassium chloride, it is evident that examples of all possible dependencies of K0 and k0 upon salt concentration Biochemistry have now been observed except that of simultaneous independence of both constants.…”