scholarly journals Chemical modification studies on a lectin from winged-bean [Psophocarpus tetragonolobus (L.) DC] tubers

1988 ◽  
Vol 254 (2) ◽  
pp. 351-357 ◽  
Author(s):  
M S Shet ◽  
M Madaiah
Keyword(s):  
Acetic Anhydride ◽  
Chemical Modification ◽  
Succinic Anhydride ◽  
Structural Changes ◽  
Dicarboxylic Acids ◽  
Winged Bean ◽  
Amino Groups ◽  
Reductive Methylation ◽  
Tryptophan Residues ◽  
Haemagglutinating Activity

The effect of chemical modification on a D(+)-galactose-specific lectin isolated from winged-bean tubers was investigated to identify the type of amino acid involved in its haemagglutinating activity. Various anhydrides of dicarboxylic acids, such as acetic anhydride, succinic anhydride, maleic anhydride and citraconic anhydride, modified 57-68% of the amino groups of the winged-bean tuber lectin. Treatment with N-acetylimidazole modified only 45% of the total amino groups. Reductive methylation of free amino groups modified 57% of the amino groups. Modification of the amino groups of the lectin by acetic anhydride and succinic anhydride did not lead to any significant change in the haemagglutinating activity (greater than or equal to 75% active). However, citraconylation and maleylation of the lectin led to a significant decrease in the haemagglutinating activity (less than or equal to 20% active). Acetylation and succinylation (3-carboxypropionylation) of the lectin led to a decrease in the pI value of the native lectin from approx. 9.5 to approx. 4.5. Treatment of the lectin with N-bromosuccinimide led to the modification of two and four tryptophan residues per molecule in the absence and in the presence of 8 M-urea respectively. The immunological identity of all the modified lectin preparations showed no gross structural changes except the lectin modified with N-bromosuccinimide in the presence of urea at pH 4.0.

Chemical Modification of the Hemolytic Lectin CEL-III by Succinic Anhydride: Involvement of Amino Groups in the Oligomerization Process

1998 ◽  
Vol 62 (6) ◽  
pp. 1185-1189 ◽  
Author(s):  
Tomomitsu HATAKEYAMA ◽  
Yumiko MATSUYAMA ◽  
Takako FUNADA ◽  
Sachiko FUKUYAMA ◽  
Hiromiki KUWAHARA ◽  
...  
Keyword(s):  
Chemical Modification ◽  
Succinic Anhydride ◽  
Amino Groups

scholarly journals Effect of succinylation (3-carboxypropionylation) on the conformation and immunological activity of ovalbumin

1976 ◽  
Vol 155 (1) ◽  
pp. 171-180 ◽  
Author(s):  
S A Kidwai ◽  
A A Ansari ◽  
A Salahuddin
Keyword(s):  
Chemical Modification ◽  
Conformational Change ◽  
Intrinsic Viscosity ◽  
Antigenic Determinants ◽  
Amino Groups ◽  
Immunological Activity ◽  
Tryptophan Residues ◽  
Lysine Residues ◽  
Stokes Radius ◽  
The Difference

The epsilon-amino groups of ovalbumin were modified with succinic anhydride; as many as 16 lysine residues were succinylated (3-carboxypropionylated). The five succinylated derivatives thus prepared were homogeneous with respect to the extent of chemical modification as shown by electrophoretic and immunological data. Succinylation of the amino groups altered electrophoretic mobility and isoionic pH of ovalbumin in the expected direction. U.v.-absorption and fluorescence spectra suggested changes in the microenvironment of the chromophores in the modified proteins. The difference-spectral results showed greater exposure of tyrosine and tryptophan residues in the succinylated ovalbumin. Increase in susceptibility to tryptic digestion, Stokes radius and intrinsic viscosity of native ovalbumin, which was observed on successive increase in the chemical modification, demonstrated a conformational change that was proportional to the extent of modification. The loss of immunological reactivity caused by chemical modification also indicated a conformational change in succinylated ovalbumin. The fact that the intrinsic viscosity of maximally modified ovalbumin was less than one-third of that for the completely denatured protein in 6M-guanidinium chloride suggested that the modified protein contained significant residual native structure. The latter presumably accommodates some antigenic determinants accounting for 37% residual immunological activity observed with maximally succinylated ovalbumin.

scholarly journals Chemical modification of sarcoplasmic reticulum. Stimulation of Ca2+ release

1986 ◽  
Vol 240 (2) ◽  
pp. 509-517 ◽  
Author(s):  
V Shoshan-Barmatz
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Acetic Anhydride ◽  
Atpase Activity ◽  
Chemical Modification ◽  
Amino Groups ◽  
Reactive Group ◽  
Rapid Release ◽  
Sarcoplasmic Reticulum Membrane ◽  
Positively Charged ◽  
Stimulation Of

Pretreatment of sarcoplasmic membranes with acetic or maleic anhydrides, which interact principally with amino groups, resulted in an inhibition of Ca2+ accumulation and ATPase activity. The presence of ATP, ADP or adenosine 5′-[beta, gamma-imido]triphosphate in the modification medium selectively protected against the inactivation of ATPase activity by the anhydride but did not protect against the inhibition of Ca2+ accumulation. Acetic anhydride modification in the presence of ATP appeared to increase specifically the permeability of the sarcoplasmic reticulum membrane to Ca2+ but not to sucrose, Tris, Na+ or Pi. The chemical modification stimulated a rapid release of Ca2+ from sarcoplasmic reticulum vesicles passively or actively loaded with calcium, from liposomes reconstituted with the partially purified ATPase fraction but not from those reconstituted with the purified ATPase. The inactivation of Ca2+ accumulation by acetic anhydride (in the presence of ATP) was rapid and strongly pH-dependent with an estimated pK value above 8.3 for the reactive group(s). The negatively charged reagents pyridoxal 5-phosphate and trinitrobenzene-sulphonate, which also interact with amino groups, did not stimulate Ca2+ release. Since these reagents do not penetrate the sarcoplasmic reticulum membranes, it is proposed that Ca2+ release is promoted by modification of internally located, positively charged amino group(s).

Studies of Glutamate Dehydrogenase: Chemical Modification and Quantitative Determination of Tryptophan Residues

1974 ◽  
Vol 43 (2) ◽  
pp. 319-325 ◽  
Author(s):  
Veit Witzemann ◽  
Rudolf Koberstein ◽  
Horst Sund ◽  
Ihab Rasched ◽  
Hans Jornvall ◽  
...  
Keyword(s):  
Chemical Modification ◽  
Quantitative Determination ◽  
Glutamate Dehydrogenase ◽  
Tryptophan Residues

scholarly journals Probing the role of tryptophan residues in a cellulose-binding domain by chemical modification

1996 ◽  
Vol 5 (11) ◽  
pp. 2311-2318 ◽  
Author(s):  
Mark R. Bray ◽  
Neil R. Gilkes ◽  
Douglas G. Kilburn ◽  
R. Antony J. Warren ◽  
Lawrence P. Mcintosh ◽  
...  
Keyword(s):  
Chemical Modification ◽  
Binding Domain ◽  
Cellulose Binding Domain ◽  
Tryptophan Residues ◽  
Cellulose Binding

scholarly journals Chemical modification of the adeno-associated virus capsid to improve gene delivery

2020 ◽  
Vol 11 (4) ◽  
pp. 1122-1131 ◽  
Author(s):  
Mathieu Mével ◽  
Mohammed Bouzelha ◽  
Aurélien Leray ◽  
Simon Pacouret ◽  
Mickael Guilbaud ◽  
...  
Keyword(s):  
Gene Delivery ◽  
Chemical Modification ◽  
Neutralizing Antibodies ◽  
Cell Tropism ◽  
Amino Groups ◽  
Chemical Modifications ◽  
Virus Capsid ◽  
Adeno Associated Virus

Bioconjugated AAV vectors, achieved by coupling of ligands on amino groups of the capsid, are of great interest for gene delivery. Chemical modifications can be used to enhance cell tropism and to decrease interactions with neutralizing antibodies.

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