Linked Life Data

2844226

Source:http://linkedlifedata.com/resource/pubmed/id/2844226

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
12
pubmed:dateCreated
1988-11-18
pubmed:abstractText
A 17-kilodalton (kDa) human placental acid phosphatase was purified 21,400-fold to homogeneity. The enzyme has an isoelectric point of pH 7.2 and a specific activity of 106 mumol min-1 mg-1 using p-nitrophenyl phosphate as a substrate at pH 5 and 37 degrees C. This placental acid phosphatase showed activity toward phosphotyrosine and toward phosphotyrosyl proteins. The pH optima of the enzyme with phosphotyrosine and with phosphotyrosyl band 3 (from human red cells) were between pH 5 and 6 and pH 5 and 7, respectively. The Km for phosphotyrosine was 1.6 mM at pH 5 and 37 degrees C. Phosphotyrosine phosphatase activity was not inhibited by tartrate or fluoride, but vanadate, molybdate, and zinc ions acted as strong inhibitors. Enzyme activity was also inhibited by DNA, but RNA was not inhibitory. It is a hydrophobic nonglycoprotein containing approximately 20% hydrophobic amino acids. The average hydrophobicity was calculated to be 903 cal/mol. The absorption coefficient at 280 nm, E1% 1cm, was determined to be 5.7. The optical ellipticity of the enzyme at 222 nm was -5200 deg cm2 dmol-1, which would correspond to a low helical content. Free sulfhydryl and histidine residues were necessary for the enzyme activity. The enzyme contained four reactive sulfhydryl groups. Chemical modification of the sulfhydryls with iodoacetate resulted in unfolding of the protein molecule as detected by fluorescence emission spectroscopy. Antisera against both the native and the denatured protein were able to immunoprecipitate the native enzyme. However, upon denaturation, the acid phosphatase lost about 70% of the antigenic determinants. Both antisera cross-reacted with a single 17-kDa polypeptide on immunoblotting.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
14
pubmed:volume
27
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
4265-73
pubmed:dateRevised
2007-11-15
pubmed:meshHeading
pubmed:year
1988
pubmed:articleTitle
Purification and physicochemical characterization of a human placental acid phosphatase possessing phosphotyrosyl protein phosphatase activity.
pubmed:affiliation
Chemistry Department, Purdue University, West Lafayette, Indiana 47907.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.