Characterization of human liver (4-methylumbelliferyl-α-d-N-acetylneuraminic acid) neuraminidase activity

The four major isoelectric forms of human liver neuraminidase (with pI values between 3.4 and 4.8) have been isolated by preparative isoelectric focusing and characterized with regard to their substrate specificity using glycoprotein, glycopeptide, oligosaccharide and ganglioside natural substrates. All forms exhibited a rather broad linkage specificity and were capable of hydrolyzing sialic acid glycosidically linked alpha 2-3, alpha 2-6 and alpha 2-8, although differential rates of hydrolysis of the substrates were found for each form. The most acidic form 1 (pI 3.4) was most active on sialyl-lactose, whereas form 2 (pI 3.9) and 3 (pI 4.4) were most active on the more hydrophobic ganglioside substrates. Form 4 (pI 4.8) was most active on the low-Mr hydrophilic substrates (fetuin glycopeptide, sialyl-lactose). Each form was less active on the glycoprotein fetuin than on a glycopeptide derived from fetuin. Organelle-enriched fractions were prepared from fresh human liver tissue and neuraminidase activity on 2′-(4-methylumbelliferyl)-alpha-D-N-acetylneuraminic acid was recovered in plasma membrane, microsomal, lysosomal and cytosolic preparations. Isoelectric focusing of the neuraminidase activity recovered in each of these preparations resulted in significantly different isoelectric profiles (number, relative amounts and pI values of forms) for each preparation. The differential substrate specificity of the isoelectric forms and the different isoelectric focusing profiles of neuraminidase activity recovered in subcellular-enriched fractions suggest that specific isoelectric forms with broad but defined substrate specificity are enriched at separate sites within the cell.

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Characterization of brimonidine metabolism with rat, rabbit, dog, monkey and human liver fractions and rabbit liver aldehyde oxidase

Xenobiotica ◽

10.3109/00498259609062804 ◽

1996 ◽

Vol 26 (1) ◽

pp. 1035-1055 ◽

Cited By ~ 10

Author(s):

A. A. Acheampong ◽

D-S. Chien ◽

S. Lam ◽

S. Vekich ◽

A. Breau ◽

...

Keyword(s):

Human Liver ◽

Aldehyde Oxidase ◽

Rabbit Liver

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Isolation and characterization of the apolipoprotein E receptor from canine and human liver.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(17)35655-7 ◽

1986 ◽

Vol 261 (9) ◽

pp. 4256-4267 ◽

Cited By ~ 10

Author(s):

D Y Hui ◽

W J Brecht ◽

E A Hall ◽

G Friedman ◽

T L Innerarity ◽

...

Keyword(s):

Apolipoprotein E ◽

Human Liver ◽

Isolation And Characterization

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Purification and characterization of cytochrome P-450-dependent arachidonic acid epoxygenase from human liver.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(18)69240-3 ◽

1988 ◽

Vol 263 (5) ◽

pp. 2536-2542

Author(s):

M Laniado-Schwartzman ◽

K L Davis ◽

J C McGiff ◽

R D Levere ◽

N G Abraham

Keyword(s):

Arachidonic Acid ◽

Human Liver ◽

Purification And Characterization ◽

Cytochrome P 450

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Characterization of human liver 3-O-beta-D-glucopyranuronosyl-cholesterol by mass spectrometry and nuclear magnetic resonance spectroscopy.

The Journal of Lipid Research ◽

10.1016/s0022-2275(20)37721-x ◽

1984 ◽

Vol 25 (10) ◽

pp. 1117-1123

Author(s):

I A Muhiudeen ◽

T A Koerner ◽

B Samuelsson ◽

Y Hirabayashi ◽

R DeGasperi ◽

...

Keyword(s):

Mass Spectrometry ◽

Nuclear Magnetic Resonance ◽

Magnetic Resonance ◽

Magnetic Resonance Spectroscopy ◽

Nuclear Magnetic Resonance Spectroscopy ◽

Human Liver ◽

Resonance Spectroscopy ◽

Nuclear Magnetic

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Characterization of glycopeptides derived from the low-density lipoprotein of hen's egg yolk

Canadian Journal of Biochemistry ◽

10.1139/o68-147 ◽

1968 ◽

Vol 46 (8) ◽

pp. 983-988 ◽

Cited By ~ 6

Author(s):

J. Z. Augustyniak ◽

W. G. Martin

Keyword(s):

Low Density Lipoprotein ◽

Density Lipoprotein ◽

Egg Yolk ◽

Low Density ◽

Amide Nitrogen ◽

Acetylneuraminic Acid ◽

Hen’S Egg ◽

Terminal Amino ◽

Protein Moiety

Two glycopeptides (A and B) were isolated from pronase-digested vitellenin, the protein moiety of the low-density lipoprotein of hen's egg yolk. Aspartic acid was the only N-terminal amino acid of both glycopeptides but only A contained N-acetylneuraminic acid. A contained 55% hexose (mannose), 14% hexosamine, 12% N-acetylneuraminic acid, 0.71% amide nitrogen, and its molecular weight was 2.3 × 103. The corresponding values for B were 64, 17, 0.0, 0.75, and 2.0 × 103. Chemical analyses showed that B (and probably A) occurs in vitellenin with the heteropolysaccharide group bound N-glycosidically via the β-amide group of an asparaginyl residue. The indicated structure is R∙(NH)Asp∙Thr∙Ser∙(Ala, Gly, Val)∙Ile, where R, the heteropolysaccharide group, contains 2 hexosamine and 8 hexose residues.

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