| Autor: |
Lojda, Zdeněk, Slabý, Jan, Kraml, Jiří, Kolínská, Jiřina |
| Zdroj: |
Histochemie; 1973, Vol. 34 Issue 4, p361-369, 9p |
| Abstrakt: |
The splitting of 6-Br-2-naphthyl-, α-naphthyl-, and 4-Cl-5-Br-3-indolyl-glycosides which proved useful for the assessment of cytological localization of intestinal enzymes in previous studies was investigated using isolated human and rat intestinal disaccharidases as a source of enzyme activities. Previous findings based on histochemical studies were confirmed and extended. 6-Br-2naphthyl α-D-glucoside is cleaved by glucoamylase and sucrase-isomaltase. The participatio of trehalase in splitting of this substrate is very low and can be neglected. The mentioned α-glucosidases are responsible for the brush border staining of enterocytes with this substrate when unfixed cold microtome sections are used. Even when a differential heat inactivation of sucrase-isomaltase and of glucoamylase occurs during paraffin embedding (so that the staining in paraffin sections is due mostly to glucoamylase) the use of natural substrates is desirable for a more precise assessment of sucrase-isomaltase activity (but without the possibility of a correct localization). 4-Cl-5-Br-3-indolyl- β-D-fucoside is the substrate of choice for the demonstration of lactase. Even when this substrate is split also by 'hetero- β-galactosidase' and by acid (lysosomal) β-galactosidase these activities do not disturb the histochemical demonstration of lactase. If however some doubts arise, the inhibition with p-Cl-mercuribenzoate (2 · 10 M) is to be emloyed (lactase activity is not inhibited). Due to a low K and a high V of indolyl-fucoside and due to its extreme stability in solution (which enables to use the substrate solution repeatidly) this substrate is suitable in routine practice even though it is expensive. α-naphthyl- and 4-Cl-5-Br-3-indolyl- β-D-glucosides are split by lactase and β-glucosidase. Due to the fact that the mutual delineation of these activities is not easy and that K an V for lactase are not so favourable as in the case of fucoside these substrates are not recommended for the assessment of lactase. 6-Br-2-naphthyl- β-D-glucoside is the substrate of choice for the histochemical studies concerned with 'hetero- β-galactosidase' and 4-Cl-5-Br-3-indolyl- β-D-galactoside for acid β-galactosidase. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
|
