Acid-base and metal ion complex formation properties of polymers containing amino acid residues

1986 ◽  
Vol 19 (1) ◽  
pp. 37-42 ◽  
Author(s):  
Rolando Barbucci ◽  
Mario Casolaro ◽  
Mila Nocentini ◽  
Silvia Corezzi ◽  
Paolo Ferruti ◽  
...  
Keyword(s):  
Amino Acid ◽  
Complex Formation ◽  
Metal Ion ◽  
Amino Acid Residues ◽  
Acid Base ◽  
Polymers Containing Amino Acid ◽  
Metal Ion Complex

Amino Acid Residues His183 and Glu264 inBacillus subtilisFerrochelatase Direct and Facilitate the Insertion of Metal Ion into Protoporphyrin IX†,‡

Biochemistry ◽  
2007 ◽  
Vol 46 (1) ◽  
pp. 87-94 ◽  
Author(s):  
Mattias D. Hansson ◽  
Tobias Karlberg ◽  
Muhammad Arys Rahardja ◽  
Salam Al-Karadaghi ◽  
Mats Hansson
Keyword(s):  
Amino Acid ◽  
Metal Ion ◽  
Protoporphyrin Ix ◽  
Amino Acid Residues

scholarly journals Acid dissociation constants of glycopeptides

1977 ◽  
Vol 163 (1) ◽  
pp. 31-38 ◽  
Author(s):  
B M Austen ◽  
R D Marshall
Keyword(s):  
Amino Acid ◽  
Dissociation Constants ◽  
Acid Dissociation ◽  
Hydroxyl Group ◽  
Amino Acid Residues ◽  
Acid Base ◽  
Titration Curves ◽  
Pka Value ◽  
Hen’S Egg ◽  
Additional Amino Acid

Glycopeptides containing mainly four amino acid residues in the sequence Asn-Leu-Thr-Ser, with small amounts of additional amino acid residues, were isolated from enzymic hydrolysates of hen's-egg albumin. Heterogeneity of the carbohydrate moiety was confirmed. Acid-base titrations showed that the alpha-amino group has a pKa value of 6.43 at 25 degrees C. The standard free engery and entropy changes associated with the ionization at 25 degrees C were 37.2kJ-mol-1 and -0.014kJ-mol-1- K-1 respectively. The complications arising in the interpretation of titration curves of the glycopeptides, which are heterogeneous with respect to the peptide chain, were considered and discussed in the light of the earlier suggestion that the titration curve of the glycopeptide might be interpreted as being due in part to a structure in which the hydroxyl group of the threonine residue is hydrogen-bonded to the beta-aspartamido oxygen atom [Neuberger & Marshall (1968) in Symposium on Foods - Carbohydrates and their Roles (Schultz, H.W., Cain, R.F. & Wrolstad, R.W., eds.), pp. 115-132, Avi Publishing Co., Westport, CT]. It is concluded that either the glycopeptides do not contain a hydrogen bond of that type, or, if they do, that it cannot be recognized by acid-base-titration studies.

scholarly journals Decoding Essential Amino Acid Residues in the Substrate Groove of a Non-Specific Nuclease from Pseudomonas syringae

Catalysts ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 941 ◽  
Author(s):  
Lynn Sophie Schwardmann ◽  
Sarah Schmitz ◽  
Volker Nölle ◽  
Skander Elleuche
Keyword(s):  
Amino Acid ◽  
Pseudomonas Syringae ◽  
Metal Ion ◽  
Homology Model ◽  
Downstream Processing ◽  
Outer Ring ◽  
Amino Acid Residues ◽  
Independent Manner ◽  
Identify Amino Acid ◽  
Close Proximity

Non-specific nucleases (NSN) are of interest for biotechnological applications, including industrial downstream processing of crude protein extracts or cell-sorting approaches in microfabricated channels. Bacterial nucleases belonging to the superfamily of phospholipase D (PLD) are featured for their ability to catalyze the hydrolysis of nucleic acids in a metal-ion-independent manner. In order to gain a deeper insight into the composition of the substrate groove of a NSN from Pseudomonas syringae, semi-rational mutagenesis based on a structure homology model was applied to identify amino acid residues on the protein’s surface adjacent to the catalytic region. A collection of 12 mutant enzymes each with a substitution to a positively charged amino acid (arginine or lysine) was produced in recombinant form and biochemically characterized. Mutations in close proximity to the catalytic region (inner ring) either dramatically impaired or completely abolished the enzymatic performance, while amino acid residues located at the border of the substrate groove (outer ring) only had limited or no effects. A K119R substitution mutant displayed a relative turnover rate of 112% compared to the original nuclease. In conclusion, the well-defined outer ring of the substrate groove is a potential target for modulation of the enzymatic performance of NSNs belonging to the PLD superfamily.

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