Table 3.

Comparison of the rate of hydrolysis of MCA-62-70 substrate in different age groups of human and young bovine lens extracts.

Type of lens	Cortex		Nucleus
	Specific activity (nmoles/mg protein/h)	Total activity in cortex (nmoles/h)	Specific activity (nmoles/h) protein/h)	Total activity in nucleus (nmoles/mg
Human young (20 years)	0.28 ± 0.04**	7.86 ± 0.89	0.043 ± 0.003**	0.98 ± 0.07
Human middle aged (40 years)	0.37 ± 0.04***	6.50 ± 0.78	0.032 ± 0.001***	0.76 ± 0.05
Human old aged (60 years)	0.29 ± 0.02**	4.92 ± 0.27	0.037 ± 0.001**	0.57 ± 0.02
Bovine young	0.68 ± 0.07***	95.87 ± 3.26	0.035 ± 0.001***	7.53 ± 0.31

Water-soluble cortical and nuclear extracts (1 mg protein) of young, middle-aged and old human lenses were incubated with MCA-62-70 substrate (25 μg) at 37 °C for 2 h. Difference in fluorescence intensity was measured before and after incubation in a spectrofluorometer after excitation at 326 nm and emission at 398 nm. The amount of MCA-62-70 hydrolyzed was calculated by extrapolation of standard graph prepared by tryptic digestion of different concentrations of MCA-62-70 substrate. The values presented are average ± SE of four independent experiments. The data was analyzed by one-way ANOVA followed by Tukey’s multiple comparison test where **p<0.001 and ***p<0.0001, compared within lens groups of cortex and nucleus. Differences between lens groups of different ages were not significant.