Linked Life Data

8514787

Source:http://linkedlifedata.com/resource/pubmed/id/8514787

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
18
pubmed:dateCreated
1993-7-22
pubmed:abstractText
The giant extracellular hemoglobin of the earthworm, Lumbricus terrestris, has four major O2-binding chains, a, b, and c (forming a disulfide-linked trimer) and d ("monomer"). Participation of additional "linker" chains L1, L2, and L3 is necessary for the assembly of the approximately 3,900+ kDa two-tiered hexagonal structure. We have determined the proportions of linker chains, trimer, and chain d in the hemoglobin by reverse phase high performance liquid chromatography which resolves all of the components and also permits simultaneous determination of the heme content. The proportions of components were determined by two independent procedures: integration of the absorbance peaks at 220 nm and amino acid analysis of the peak fractions. The results indicate that the weight proportion of linker chains is 0.163 +/- 0.023. This value, together with molecular masses determined both by amino acid sequence analysis and by matrix-assisted laser desorption mass spectrometry, gives a molar ratio of abcd chains to linkers of 8:1, corresponding to the minimal unit (abcd)2.L. This ratio suggests that 24 (abcd)2 units and 24 linker chains form the complete structure with a total calculated mass of polypeptide of 3,975 kDa with hemes on chains a, b, c and d and on one linker. The calculated heme content is 3.1% not including carbohydrate. This accounts for a measured heme content of 3.0% on a polypeptide basis. Additional mass (approximately 133 kDa, 3.4%), attributed to carbohydrate, brings the total mass to 4,108 kDa with a minimum molecular mass/heme of 20,500 Da. The presence of equimolar quantities of three unique linker chains means that the apparent one-twelfth structural units seen by electron microscopy cannot all be identical.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
25
pubmed:volume
268
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
13539-47
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1993
pubmed:articleTitle
The extracellular hemoglobin of the earthworm, Lumbricus terrestris. Determination of subunit stoichiometry.
pubmed:affiliation
Department of Zoology, University of Texas, Austin 78712.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, U.S. Gov't, Non-P.H.S.