Linked Life Data

10801339

Source:http://linkedlifedata.com/resource/pubmed/id/10801339

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
19
pubmed:dateCreated
2000-6-27
pubmed:abstractText
The metal-catalyzed oxidation (ascorbate/cupric chloride/oxygen) of recombinant human relaxin (rhRlx, type II) was shown by Li et al. [Li, S., Nguyen, T. H., Schöneich, C., and Borchardt, R. T. (1995) Biochemistry 34, 5762-5772] to result in the chemical modification of His A(12), Met B(4), and Met B(25). Considering the fact that His A(12) exists in an extended loop that joins two alpha-helices in this protein, we hypothesized that oxidation of this specific amino acid leads to alterations in the secondary and tertiary structures of the protein, resulting in the pH-dependent aggregation/precipitation phenomena observed in our earlier studies (i.e., at pH >6.0 most of the degradants of rhRlx are insoluble). Evidence obtained in the current study that supports this hypothesis includes the following: (i) oxidation of rhRlx with hydrogen peroxide (H(2)O(2)), which leads only to modification of Met B(4) and Met B(25), does not result in the pH-dependent aggregation/precipitation of the protein; and (ii) metal-catalyzed oxidation of porcine relaxin (pRlx), which does not contain His at position A(12), leads to chemical degradation of the protein [e.g., Met A(2) is oxidized] but produces only slight pH-dependent aggregation/precipitation of the protein. In addition, experimental evidence is provided to show that the physical instability of rhRlx observed at pH >6.0 does not appear to be related to the pH-dependent solubility of a common protein degradant. Instead, it appears that several oxidation products of His A(12) are produced in a pH-dependent manner and that these oxidation products produce different effects on the physical stability of the protein. Evidence in support of this conclusion includes the observation that the soluble degradants of rhRlx showed reduced levels of His, reduced levels of the T(2)-T(7) tryptic fragment that contained His A(12), and the presence of 2-oxo-His. Similarly, the precipitated degradants of rhRlx showed reduced levels of His but no 2-oxo-His. In addition, the soluble degradants, which contain 2-oxo-His, appear to exist as monomers having an average molecular weight similar to that of rhRlx. These results suggest that the metal-catalyzed oxidation of His A(12) leads to other, as yet unidentified oxidation products of His A(12) that affect the secondary/tertiary structure of the protein more significantly than does 2-oxo-His and ultimately lead to the physical instability of the protein observed at higher pH values.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
May
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
16
pubmed:volume
39
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
5876-85
pubmed:dateRevised
2009-11-19
pubmed:meshHeading
pubmed-meshheading:10801339-Amino Acids, pubmed-meshheading:10801339-Animals, pubmed-meshheading:10801339-Ascorbic Acid, pubmed-meshheading:10801339-Catalysis, pubmed-meshheading:10801339-Chemical Precipitation, pubmed-meshheading:10801339-Chromatography, Liquid, pubmed-meshheading:10801339-Copper, pubmed-meshheading:10801339-Histidine, pubmed-meshheading:10801339-Humans, pubmed-meshheading:10801339-Hydrogen Peroxide, pubmed-meshheading:10801339-Hydrogen-Ion Concentration, pubmed-meshheading:10801339-Mass Spectrometry, pubmed-meshheading:10801339-Oxidation-Reduction, pubmed-meshheading:10801339-Peptide Fragments, pubmed-meshheading:10801339-Peptide Mapping, pubmed-meshheading:10801339-Recombinant Proteins, pubmed-meshheading:10801339-Relaxin, pubmed-meshheading:10801339-Solubility, pubmed-meshheading:10801339-Swine
pubmed:year
2000
pubmed:articleTitle
Evidence for the involvement of histidine A(12) in the aggregation and precipitation of human relaxin induced by metal-catalyzed oxidation.
pubmed:affiliation
Department of Pharmaceutical Chemistry, The University of Kansas, Lawrence, Kansas 66047, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.