Cleavage of oligosaccharides by rat kidney sialidase Influence of substrate structure

Abstract

The specificity of the sialidase activity present in rat kidney cortex (12 000 × g pellet) was studied with various tritiated oligosaccharidic substrates: (i) αNeuAc2 → 3βGall → 4Glc‐itol[3H], αNeuAc2 → 6βGall → 4Glc‐itol[3H] and αNeuAc2 → 8αNeuAc2 → 3βGall → 4Glc‐itol[3H] from bovine colostrum; (ii) α‐NeuAc2 → 6βGall → 4βGlcNAc‐itol[3H], αNeuAc2 → 3βGal1 → 4βGlcNAcl → 2αManl → 3βMan1 → 4GlcNAc‐itol[3H]. αNeuAc2 → 6βGall → 4βGlcNAcl → 2αManl α 3(βGall → 4GlcNAcl → 2αManl → 6)βManl → 4GlcNAc‐itol [3H]et αNeuAc2 → 6βGall → 4βGlcNAcl → 2αManl‐3(αNeuAc2 → 6βGall → 4βGlcNAcl → 2αManl → 6)βManl 4GlNAc‐itol[3H] isolated from the urine of a patient with mucolipidosis I. The enzyme cleaves α2 → 3 and α2 → 8 linkages at a greater rate than the α2 → 6 bonds. Its activity decreases with the length of the oligosaccharidic chain. Substitution of a glucose moiety by Nacetylglucosamine results in diminished activity. The specificity of rat kidney sialidase differs from that reported for other mammalian of viral sialidases.

Expression of sialidase and dystroglycan in human glomerular diseases

“…There are four subtypes of mammalian sialidase, originally characterized by their localization: lysosomal neuraminidase 1 (NEU1); cytosolic neuramidase 2; plasma membrane-associated neuramidase 3 and mitochondrial neuramidase 4. In the kidney, up to now only the biochemical activity of sialidase has been studied, showing higher activity in tubuli than in glomeruli [29,38]. Sialidase activity in isolated homogenized glomeruli was increased in streptozotocin-induced diabetes in rats and correlated with albuminuria and transferrin excretion [27,28].…”

Sex and Age Dependence of Rat Kidney Sialidase

“…This was effected as previously described [3], Briefly, the incubation sys tem contained: 100 pi of fresh enzyme preparation (approximately 150 pg protein); 0.6 nmol (25 Ci/mol) of purified radiolabeled sialyl-a(2-3)[3H]-lactitol iso mer as substrate [5]; 50 mM sodium acetate buffer pH 4 and 3 mM sodium azide in a final volume of 150 pi. The incubations were carried out at 37 °C for 10-20 min.…”

“…Rat kidney sialidase (EC 3.2.1.18) is mainly localized in the lysosomes and firmly membrane bound [1][2][3][4], In previous studies, we have described kinetic properties of the membrane-bound enzyme and its substrate specificity [3,5]. Important variations of kidney sialidase activity have been observed by us in various pathological states particu larly in diabetes [3,6,7], Besides, the in crease in sialidase activity in diabetes is as sociated with a diminished level of sialic acids which contribute to the negative charges of basement and cell membranes in…”

Sialidase in the Guinea Pig Pulmonary Parenchyma. Increased Activity in the Cytosolic and Microsomal Subcellular Fractions after Stimulation withBacillus Calmette Guérin

“…Sialidase activity has been demonstrated in various mammalian tissues, such as placenta 161 , brain 171 , liver [8] , kidney [9] , intestine 1101 . This enzymatic activity is widely distributed in both eukaryotic and prokaryotic cells.…”