Linked Life Data

2820482

Source:http://linkedlifedata.com/resource/pubmed/id/2820482

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
13
pubmed:dateCreated
1987-11-16
pubmed:abstractText
The membrane fusion activity of melittin and its succinylated derivative was studied as a function of pH by the transfer of spin-labeled phosphatidylcholine as well as by internal content mixing and electron microscopy. The protonation process of the carboxyl groups introduced into melittin was studied by 13C NMR spectroscopy using derivative prepared with [1,4(-13)C]succinic anhydride. Melittin causes fusion of sonicated phosphatidylcholine vesicles in a wide range of pH. In marked contrast, melittin with all four amino groups succinylated induces fusion only at acidic pH lower than 5.2, with the maximum at pH 5.1. The fusion reactions are very rapid, reaching a saturation level within 1 min. The fusion efficiency depends on the peptide-to-phospholipid ratio in the reaction mixture. Trypsinized succinylated melittin, which has lost the four positively charged C-terminal residues, causes aggregation of vesicles at acidic pH but cannot induce fusion. The 13C NMR peaks for the carboxyl and carbonyl groups of succinylated melittin shifted to higher field as the pH was lowered. The pKa value of the four carboxyl groups was obtained as 5.19 and 4.83 in the presence and absence of vesicles, respectively. The pKa value in the presence of vesicles agrees quite well with the half-maximal pH for fusion of 5.15, indicating that the fusion activity is triggered by protonation of the carboxyl groups in the hydrophobic segment of the peptide. The higher shift of pKa value in the presence of vesicles can be due to stabilization of the protonated form by entrance into lipid bilayer hydrocarbon layer.(ABSTRACT TRUNCATED AT 250 WORDS)
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
30
pubmed:volume
26
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
4056-62
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1987
pubmed:articleTitle
Membrane fusion activity of succinylated melittin is triggered by protonation of its carboxyl groups.
pubmed:affiliation
Department of Biophysics, Faculty of Science, Kyoto University, Japan.
pubmed:publicationType
Journal Article, Comparative Study