Gene/Protein
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Drug
Enzyme
Compound
Pivot Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Target Concepts:
Gene/Protein
Disease
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Enzyme
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Query: UMLS:C0027960 (
mole
)
21,279
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
The digestion of EF-Tu-GDP (or EF-Tu-GTP) by trypsin [EC 3.4.21.4] under native conditions has been shown to proceed through two different and characteristic stages. 1. In the first phase, the protein is transformed into a fragment (Fragment A) with a molecular weight of 39,000 by exposure to trypsin for a relatively short period of time. Fragment A is unable to catalyze the binding of aminoacyl-tRNA to ribosomes. The ability to promote two partial steps of the binding reaction, i.e., formation of the aminoacyl-tRNA-EF-Tu-GTP ternary complex as well as the methanol-stimulated, ribosome dependent GTPase reaction, was rapidly destroyed. On the other hand, the ability to interact with guanine nucleotides as well as EF-Ts survived well during prolonged digestion. 2. In the second phase of digestion, a nick is introduced in Fragment A to yield two subfragments (Fragments B and C). These two fragments exist as a hybrid molecule which migrates as a single peak on a Sephadex G-75 column, and which dissociates into Fragments B and C only in the presence of 6 M guanidine hydrochloride or 5% sodium dodecyl sulfate. The molecular weights of Fragments B and C, as determined by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate, were 22,000 and 12,000 respectively. The hybrid molecule still retained one
mole
of bound guanine nucleotide and was resistant to further tryptic digestion. 3. Three sulfhydryl groups of EF-Tu were found to be present in Fragment B, both by amino acid analysis of the purified fragments and also by electrophoresis of tryptic digests labeled with N-ethyl[14C]maleimide. 4. The tryptic digestion of EF-Tu-GDP (or EF-Tu-GTP) labeled with N-(1-anilinonaphthyl-4)maleimide (
ANM
) at SH2 (the second SH), caused a 30% decrease in the fluorescence emission during the first rapid phase of digestion. This indicates that destruction of the hydrophobic environment near SH2 of EF-Tu occurred in the early phase of tryptic digestion. 5. The kinetic studies on the reaction of
ANM
with EF-Tu before and after tryptic digestion indicated that both Fragment A and the hybrid molecule reacted with
ANM
in the presence of GTP three to four times more rapidly than in the presence of GDP. Thus, it appears that the ability to induce conformational transition near SH2 by a change of nucleotide ligands is still retained in the hybrid molecule consisting of Fragments B and C.
...
PMID:Limited hydrolysis of the polypeptide chain elongation factor Tu by trypsin. Isolation and characterization of the polypeptide fragments. 93 63
N-(1-Anilinonaphthyl-4)maleimide (
ANM
) (m.p. 207-208.5 degrees C), nonfluorescent, reacts selectively with thiols to give addition products which are strongly fluorescent (excitation maximum 355 nm, emission maximum 448 nm, in ethanol). 0.7
mole
of
ANM
was introduced into thiol groups of egg albumin without modifying any other amino acid residues. In the fluorescence spectra of the reaction products of
ANM
with thiols, the quantum yields increase and the emission maxima shift towards the blue as the solvent polarity decreases. This remarkable solvent dependence was described in terms ofZ value of the solvents.
ANM
is thus expected to be a useful fluorescent hydrophobic probe directed to thiol groups in protein.
...
PMID:Fluorescent thiol reagents. VI. N-(1-Anilinonaphthyl-4)maleimide; a fluorescent hydrophobic probe directed to thiol groups in protein. 1999 39
