Linked Life Data

3663587

Source:http://linkedlifedata.com/resource/pubmed/id/3663587

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
14
pubmed:dateCreated
1987-12-7
pubmed:abstractText
13C NMR has been used to observe the equilibrium complex of [4-13C]-5-aminolevulinate ([4-13C]ALA) bound to porphobilinogen (PBG) synthase (5-aminolevulinate dehydratase), a 280,000-dalton protein. [4-13C]ALA (chemical shift = 205.9 ppm) forms [3,5-13C]PBG (chemical shifts = 121.0 and 123.0 ppm). PBG prepared from a mixture of [4-13C]ALA and [15N]ALA was used to assign the 121.0 and 123.0 ppm resonances to C5 and C3, respectively. For the enzyme-bound equilibrium complex formed from holoenzyme and [4-13C]ALA, two peaks of equal area with chemical shifts of 121.5 and 127.2 ppm are observed (line widths approximately 50 Hz), indicating that the predominant species is probably a distorted form of PBG. When excess free PBG is present, it is in slow exchange with bound PBG, indicating an exchange rate of less than 10 s-1, which is consistent with the turnover rate of the enzyme. For the complex formed from [4-13C]ALA and methyl methanethiosulfonate (MMTS) modified PBG synthase, which does not catalyze PBG formation, the predominant species is a Schiff base adduct (chemical shift = 166.5 ppm, line width approximately 50 Hz). Free ALA is in slow exchange with the Schiff base. Activation of the MMTS-modified enzyme-Schiff base complex with 113Cd and 2-mercaptoethanol results in the loss of the Schiff base signal and the appearance of bound PBG with the same chemical shifts as for the bound equilibrium complex with Zn(II) enzyme. Neither splitting nor broadening from 113Cd-13C coupling was observed.
pubmed:grant
pubmed:commentsCorrections
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
14
pubmed:volume
26
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
4258-64
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1987
pubmed:articleTitle
13C NMR studies of porphobilinogen synthase: observation of intermediates bound to a 280,000-dalton protein.
pubmed:affiliation
Department of Biochemistry, University of Pennsylvania School of Dental Medicine, Philadelphia 19104-6002.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't