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			PubMed Journals: Biochem Biophys Res Commun

  Source:		PMID: 9784398


    		Biochem Biophys Res Commun. 1998 Sep
     		29;250(3):635-41.

			Gustin from human parotid saliva is carbonic
			anhydrase VI.

			Thatcher BJ(1), Doherty AE, Orvisky E, Martin
			BM, Henkin RI.

			Author Information
			(1) Clinical Neuroscience Branch, NIMH,
			NIH, Bethesda, Maryland, USA.

			Gustin, a zinc-metalloprotein constituting
			about 3% of human parotid saliva protein
			was previously isolated and characterized
			as a single polypeptide chain of 37kDa with
			one mole of zinc tightly bound to the protein.
			It exhibited biological activity activating
			calmodulin dependent bovine brain cAMP
			phosphodiesterase and was decreased in saliva
			of patients with loss of taste in whom taste
			buds showed a specific pathological morphology.
			Determination of its primary structure by amino
			acid sequence revealed it was identical
			with carbonic anhydrase (CA) [EC 4.2.1.1]
			VI and had two N-linked glycosylation sites.
			Analysis by reverse phase HPLC and SDS-PAGE before
			and after deglycosylation confirmed a single
			peak with molecular weight of the purified
			protein being 37kDa, the deglycosylated
			protein, 33kDa. N-linked carbohydrate chains
			contained N-acetyl glucosamine, galactose,
			mannose, and fucose interior to di, tri
			and tetra sialyated termini. By isoelectric
			focusing five increasingly acidic pI values
			were determined consistent with addition
			of sialic acid as the terminal carbohydrate
			residue on the N-linked glycoforms of the
			protein. Gustin was found to exhibit CA
			activity but was inhibited by known CA inhibitors
			in a different manner than CA I or II. These
			findings, consistent with analysis of previous
			investigators, indicate that parotid saliva
			gustin is CA VI.

			Copyright 1998 Academic Press.

			DOI: 10.1006/bbrc.1998.9356 PMID: 9784398
			[Indexed for MEDLINE]

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