Send to

Choose Destination
See comment in PubMed Commons below
FASEB J. 1987 Aug;1(2):143-8.

Characterization and kinetic studies of deglycosylated dopamine beta-hydroxylase.


Dopamine beta-hydroxylase (D beta H) (EC from adrenal medulla is a glycoprotein with approximately 5% carbohydrate by weight. The oligosaccharide chains of this enzyme were enzymatically removed with various glycosidic enzymes (endoglycosidases D, F, and H; glycopeptidase F; alpha-mannosidase; neuraminidase; and beta-galactosidase). The time course of deglycosylation was monitored by polyacrylamide gel electrophoresis, and evidence for sugar removal was shown by a modification of the Western blot technique utilizing 125I-labeled concanavalin A and by amino acid analysis. Protein was detected in the gel by using specific antibodies and 125I-labeled protein A. Steady-state kinetic data of deglycosylated D beta H show minor differences between the native and the deglycosylated protein. The Km values for tyramine were 2.17 and 1.66 mM whereas the Km values for oxygen were 0.18 and 0.14 mM for the native and the deglycosylated protein, respectively. The Vmax values (pH 5.0) for the two forms of the enzyme were comparable, with the deglycosylated D beta H being 15% lower. These data indicate that the oligosaccharide moieties present on D beta H do not play a role in catalysis.

[Indexed for MEDLINE]
PubMed Commons home

PubMed Commons

How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for HighWire
    Loading ...
    Support Center