Kirkeby S
Histochemistry. 1976 Oct 22;49(2):145-55. doi: 10.1007/BF00495678.
The alpha-naphthyl acetate esterase in both group I and group II thyroid cells is shown to contain SH groups since there is a decline in activity in both cell groups when certain sulfhydryl reagents [DTNB; 5,5'-Dithiobis-(2-nitrobenzoic acid)-AgNO3-Mersalyl-PCMB (parachloro mercuribenzoate) + urea] are added to the incubation media. Thus the inhibition is by far the greatest in group I cells, which also show the greatest activity after incubation in conventional media, when long fixation and storage times are used. In all cases the inhibiting effect was complete or almost completely reversed if cysteine was added to the incubation media in equivalent concentrations to the SH blocker. There were great differences among the sulfhydryl reagents used in their ability to bring about enzyme inhibition. The alkylating agents NEM (N-ethylmaleimide) and iodoacetamide had no or little effect while PCMB could only inhibit the activity of the alpha-naphthylacetate esterase if the enzyme was denaturated with 5 M urea. The maximal inhibitory effect of PCMB was only obtained when NaCl was added to the incubation media. The most effective inhibitor was AgNO3.
I组和II组甲状腺细胞中的α-萘乙酸酯酶显示含有巯基，因为当向孵育培养基中添加某些巯基试剂[DTNB；5,5'-二硫代双-(2-硝基苯甲酸)-硝酸银-汞撒利-对氯汞苯甲酸(PCMB)+尿素]时，两组细胞的活性均下降。因此，抑制作用在I组细胞中最为明显，当使用长时间固定和储存时，I组细胞在常规培养基中孵育后也显示出最大活性。在所有情况下，如果向孵育培养基中添加与巯基阻断剂浓度相当的半胱氨酸，抑制作用完全或几乎完全逆转。所使用的巯基试剂在引起酶抑制的能力上有很大差异。烷基化剂NEM（N-乙基马来酰亚胺）和碘乙酰胺没有或只有很小的作用，而PCMB只有在酶用5M尿素变性后才能抑制α-萘乙酸酯酶的活性。只有当向孵育培养基中添加氯化钠时，PCMB才能获得最大抑制效果。最有效的抑制剂是硝酸银。
