Sequence Determination of a Protein with N-Terminal Glutamic Acid after Modification of Carboxyl Groups with Carbodiimide as the Coupling Agent

1974 ◽  
Vol 52 (6) ◽  
pp. 560-562
Author(s):  
C. Gilardeau ◽  
M. Chrétien
Keyword(s):  
Methyl Ester ◽  
Glutamic Acid ◽  
Water Soluble ◽  
Carboxyl Groups ◽  
Edman Degradation ◽  
Sequence Determination ◽  
Glutamic Acid Residue ◽  
N Terminus ◽  
Glycine Methyl Ester

Glutamine and asparagine residues in proteins can be differentiated from glutamic and aspartic residues, during the Edman degradation, after modification of the carboxyl groups by glycine methyl ester in presence of a water-soluble carbodiimide. When applied to ovine and porcine beta-lipotropic hormones, which have a glutamic acid residue at the N-terminus, the carbodiimide blocks the N-terminus. However, the Edman degradation proceeds normally, if the phenylthiocarbamyl derivative is formed prior to the modification reaction with glycine. In this communication, radioactive glycine was used to modify the carboxyl groups.

Lipotropic and Adrenocorticotropic Hormones. Biological Activities of the Carboxyl-Modified Hormones

1974 ◽  
Vol 52 (3) ◽  
pp. 723-726 ◽  
Author(s):  
C. Gilardeau ◽  
M. Chrétien ◽  
M. Lis
Keyword(s):  
Methyl Ester ◽  
Coupling Agent ◽  
Lipolytic Activity ◽  
Biological Activities ◽  
Water Soluble ◽  
Carboxyl Groups ◽  
Glycine Methyl Ester

The carboxyl groups of sheep adrenocorticotropic and beta-lipotropic hormones (ACTH and beta-LPH) were modified by glycine methyl ester and taurine using a water-soluble carbodiimide as a coupling agent. The biological activities of these derivatives were measured and compared with those of the native hormones. With ACTH, the lipolytic activity is almost unaffected although the adrenocorticotropic activity is completely destroyed. LPH partially looses its lipolytic activity.

scholarly journals Positive Charges on Lysine Residues of the Extrinsic 18 kDa Protein Are Important to Its Electrostatic Interaction with Spinach Photosystem II Membranes

2005 ◽  
Vol 37 (11) ◽  
pp. 737-742 ◽  
Author(s):  
Jin-Peng Gao ◽  
Zhen-Hua Yong ◽  
Feng Zhang ◽  
Kang-Cheng Ruan ◽  
Chun-He Xu ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Methyl Esters ◽  
Binding Activity ◽  
Water Soluble ◽  
Carboxyl Groups ◽  
Amino Groups ◽  
Charged Amino Acids ◽  
Lysine Residues ◽  
Glycine Methyl Ester ◽  
Positively Charged

Abstract To determine the contribution of charged amino acids to binding with the photosystem II complex (PSII), the amino or carboxyl groups of the extrinsic 18 kDa protein were modified with Nsuccinimidyl propionate (NSP) or glycine methyl ester (GME) in the presence of a water-soluble carbodiimide, respectively. Based on isoelectric point shift, 4–10 and 10–14 amino groups were modified in the presence of 2 and 4 mM NSP, respectively. Similarly, 3–4 carboxyl groups were modified by reaction with 100 mM GME. Neutralization of negatively charged carboxyl groups with GME did not alter the binding activity of the extrinsic 18 kDa protein. However, the NSP-modified 18 kDa protein, in which the positively charged amino groups had been modified to uncharged methyl esters, failed to bind with the PSII membrane in the presence of the extrinsic 23 kDa protein. This defect can not be attributed to structural or conformational alterations imposed by chemical modification, as the fluorescence and circular dichroism spectra among native, GME and NSP-modified extrinsic 18 kDa proteins were similar. Thus, we have concluded that the positive charges of lysyl residues in the extrinsic 18 kDa protein are important for its interaction with PSII membranes in the presence of the extrinsic 23 kDa protein. Furthermore, it was found that the negative charges of carboxyl groups of this protein did not participate in binding with the extrinsic 23 kDa protein associated with PSII membranes.

scholarly journals New renin inhibitors homologous with pepstatin

1981 ◽  
Vol 197 (2) ◽  
pp. 465-471 ◽  
Author(s):  
M Eid ◽  
G Evin ◽  
B Castro ◽  
J Menard ◽  
P Corvol
Keyword(s):  
Methyl Ester ◽  
Glutamic Acid ◽  
Water Soluble ◽  
Amino Acid Residues ◽  
Renin Inhibitors ◽  
C Terminus ◽  
Coupling Reagent ◽  
Order Of Magnitude ◽  
High Yields

Four homologues of pepstatin, the potent but poorly soluble inhibitor of aspartic proteinases, were synthesized by coupling to the C-terminus of the natural pentapeptide the following amino acid residues: L-arginine methyl ester, L-aspartic acid, L-glutamic acid and the dipeptide L-aspartyl-L-arginine. The peptide-coupling reagent we used, benzotriazolyloxytris(dimethylamino)phosphonium hexafluorophosphate, allowed us to obtain readily pure pepstatin homologues with high yields (60-83%). Pepstatylarginine methyl ester and pepstatylglutamic acid were about one order of magnitude more water-soluble than pepstatin. The four homologues and pepstatin were tested in vitro as inhibitors for highly purified pig and human renins acting on the N-acetyltetradecapeptide substrate. The 50% inhibitory concentrations (IC50) of the homologues were ranged from 0.01 to 1 microM against porcine renin at pH 6.0 (pepstatin IC50 approximately 0.32 microM) and from 5.8 to 41 microM against human renin at pH 6.5 (pepstatin IC 50 approximately 17 microM). By three different graphical methods we showed that pepstatin and the four homologues behaved as competitive inhibitors for porcine renin. The most potent inhibitors were pepstatylaspartic acid and pepstatylglutamic acid, with inhibitory constants respectively 2- and 10-fold smaller than that of pepstatin. By coupling glutamic acid to pepstatin, the ratio solubility/Ki was increased by two orders of magnitude.

scholarly journals Identification of an essential glutamic acid residue in β-lactamase II from Bacillus cereus

1986 ◽  
Vol 233 (2) ◽  
pp. 465-469 ◽  
Author(s):  
C Little ◽  
E L Emanuel ◽  
J Gagnon ◽  
S G Waley
Keyword(s):  
Glutamic Acid ◽  
Bacillus Cereus ◽  
Gel Filtration ◽  
Thiol Group ◽  
Water Soluble ◽  
Beta Lactamase ◽  
Pepsin Digestion ◽  
Early Stages ◽  
Glutamic Acid Residue ◽  
Beta Lactamase Ii

Beta-Lactamase II from Bacillus cereus was readily inactivated by incubation at pH 4.75 with a water-soluble carbodiimide plus a suitable nucleophile. In the early stages of the reaction, 1 equivalent of nucleophile was incorporated/equivalent of enzyme, whereas during the later stages a second equivalent of nucleophile was also incorporated. This latter process correlated with the blocking of the enzyme's single thiol group. Enzyme inactivated in the presence of the coloured nucleophile N-(2,4-dinitrophenyl)ethylenediamine was fragmented by pepsin digestion, and coloured peptides were isolated by gel filtration and h.p.l.c. Two major peptides, representing 52% of the incorporated label, were isolated and sequenced. Both peptides contained the incorporated label on glutamic acid-37, and it is concluded that this latter residue represents a catalytically essential carboxylic residue in beta-lactamase II.

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