Linked Life Data

11826961

Source:http://linkedlifedata.com/resource/pubmed/id/11826961

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
12
pubmed:dateCreated
2002-2-5
pubmed:abstractText
Trehalase (EC 3.2.1.28) of the bound type was purified as an electrophoretically homogeneous protein from adult honeybees by fractionation with ammonium sulfate, hydrophobic chromatography, and DEAE-Sepharose CL-6B, CM-Sepharose CL-6B, butyl-Toyopearl 650M, and p-aminophenyl beta-glucoside Sepharose 4B column chromatographies. The enzyme preparation was confirmed to be a monomeric protein containing 3.1% carbohydrate. The molecular weight was estimated to be approximately 69,000, and the optimum pH was 6.7. The Michaelis constant (Km) was 0.66 mM, and the molecular activity (k0) was 86.2 s(-1). The enzyme was an "inverting" type which produced beta-glucose from alpha, alpha-trehalose. Dependence of the V and Km values on pH gave values for the ionization constants, pKe1 and pKe2, of essential ionizable groups 1 and 2 of the free enzyme of 5.3 and 8.5, respectively. When the dielectric constant of the reaction mixture was decreased, pKe1, and pKe2 were shifted to higher values of + 0.2 and + 0.5 pH unit, respectively. The ionization heat (deltaH) of ionizable group 1 was estimated to be + 1.8 kcal/mol, and the deltaH value of group 2 was + 1.5 kcal/mol. These findings strongly support the notion that the essential ionizable groups of honeybee trehalase are two kinds of carboxyl groups, one being a dissociated type (-COO(-), ionizable group 1) and the other a protonated type (-COOH, ionizable group 2), although the pKe2 value is high.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0916-8451
pubmed:author
pubmed:issnType
Print
pubmed:volume
65
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
2657-65
pubmed:dateRevised
2003-11-14
pubmed:meshHeading
pubmed:year
2001
pubmed:articleTitle
Purification and identification of the essential ionizable groups of honeybee, Apis mellifera L., trehalase.
pubmed:affiliation
Division of Applied Bioscience, Graduate School of Agriculture, Hokkaido University, Sapporo, Japan.
pubmed:publicationType
Journal Article