Cejková J, Lojda Z
Histochemistry. 1986;84(1):67-71. doi: 10.1007/BF00493423.
The distribution of activities of membrane aminopeptidases (aminopeptidase M (APM), aminopeptidase A (APA), dipeptidyl peptidase IV (DPP IV), gamma-glutamyltransferase (GGT) and lysosomal exopeptidases (dipeptidyl peptidase I (DPP I), dipeptidyl peptidase II (DPP II)) was investigated in rabbit, ox and pig corneas. Cryostat sections of snap-frozen corneas treated with chloroform-acetone (4 degrees C) were used for the demonstration of membrane-bound enzymes and sections of corneas fixed in 4% paraformaldehyde (4 degrees C) for the demonstration of lysosomal enzymes. In activities of proteases species differences were found. The rabbit cornea was most active, followed by ox and pig corneas. Individual corneal layers reacted differently. Of membrane proteases a high APM activity was found in keratocytes, whereas epithelium and endothelium were negative. On the other hand, APA and GGT were active in the epithelium and endothelium. Their activities in keratocytes were less pronounced. DPP IV activity was demonstrated in some keratocytes beneath the epithelium only. Lysosomal enzymes DPP I and DPP II were active in all corneal layers. The epithelium displayed the highest activity. Differences in activities in the centro-peripheral and epithelio-endothelial directions were found. DPP I, DPP II, and APM were most active in the limbal region in all corneal layers.
研究了兔、牛和猪角膜中膜氨基肽酶（氨基肽酶M（APM）、氨基肽酶A（APA）、二肽基肽酶IV（DPP IV）、γ-谷氨酰转移酶（GGT））以及溶酶体外肽酶（二肽基肽酶I（DPP I）、二肽基肽酶II（DPP II））的活性分布。用氯仿-丙酮（4℃）处理的速冻角膜的冰冻切片用于显示膜结合酶，用4%多聚甲醛（4℃）固定的角膜切片用于显示溶酶体酶。在蛋白酶活性方面发现了种属差异。兔角膜活性最高，其次是牛和猪角膜。角膜各层的反应不同。在膜蛋白酶中，角膜细胞中发现高APM活性，而上皮细胞和内皮细胞呈阴性。另一方面，APA和GGT在上皮细胞和内皮细胞中具有活性。它们在角膜细胞中的活性不太明显。仅在上皮层下方的一些角膜细胞中显示出DPP IV活性。溶酶体酶DPP I和DPP II在角膜各层均有活性。上皮细胞活性最高。在中央-周边方向和上皮-内皮方向发现了活性差异。DPP I、DPP II和APM在所有角膜层的角膜缘区域活性最高。
