Amino acids and proteins
... These amino acids are not charged at physiological pH. Serine and threonine, asparagine and glutamine have polar hydroxyl groups in their side chains These can contribute to hydrogen bonding in proteins For this reason the amino acids are classed as hydrophillic. ...
... These amino acids are not charged at physiological pH. Serine and threonine, asparagine and glutamine have polar hydroxyl groups in their side chains These can contribute to hydrogen bonding in proteins For this reason the amino acids are classed as hydrophillic. ...
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... traditional site-directed mutagenesis experiments. It has been proposed for ketosteroid isomerase and other enzymes that active site hydrogen bonding groups provide energetic stabilization via “short, strong” or “low-barrier” hydrogen bonds that are formed due to matching of their pKa or proton affini ...
... traditional site-directed mutagenesis experiments. It has been proposed for ketosteroid isomerase and other enzymes that active site hydrogen bonding groups provide energetic stabilization via “short, strong” or “low-barrier” hydrogen bonds that are formed due to matching of their pKa or proton affini ...
1 Determinants of protein-protein interfaces
... intermolecular hydrogen bonds and salt bridges being the whole story. However, three of the 54 high-resolution structures studied in [29] have no hydrogen bonds or salt bridges, and another dozen have no salt bridges and five or fewer hydrogen bonds. Thus, we will delve deeper to see what other fact ...
... intermolecular hydrogen bonds and salt bridges being the whole story. However, three of the 54 high-resolution structures studied in [29] have no hydrogen bonds or salt bridges, and another dozen have no salt bridges and five or fewer hydrogen bonds. Thus, we will delve deeper to see what other fact ...
Proteinogenic amino acid
... in the diet, and so are called essential amino acids; those are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. The remaining two, selenocysteine and pyrrolysine, are incorporated into proteins by unique synthetic mechanisms. The word proteinogen ...
... in the diet, and so are called essential amino acids; those are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. The remaining two, selenocysteine and pyrrolysine, are incorporated into proteins by unique synthetic mechanisms. The word proteinogen ...
Mutations Lab
... based on whether they are hydrophobic, hydrophilic, or if they are cysteine amino acids (which will form disulfide bonds). You will then fold your chain of amino acids/strip of paper into a specific shape based on these properties (you can tape or staple your cysteine amino acids together to create ...
... based on whether they are hydrophobic, hydrophilic, or if they are cysteine amino acids (which will form disulfide bonds). You will then fold your chain of amino acids/strip of paper into a specific shape based on these properties (you can tape or staple your cysteine amino acids together to create ...
Identification of Amino Acid Substitutions that Alter the Substrate Specificity of TEM-1 b-Lactamase.
... P-Lactam antibiotics such as penicillins and cephalosporins are among the most often used antimicrobial agents. Because of the selective pressure resulting from the prevalence of j-lactam antibiotic use, bacterial resistance has increased and now represents a serious threat to antibiotic therapy (14 ...
... P-Lactam antibiotics such as penicillins and cephalosporins are among the most often used antimicrobial agents. Because of the selective pressure resulting from the prevalence of j-lactam antibiotic use, bacterial resistance has increased and now represents a serious threat to antibiotic therapy (14 ...
File
... Citrate Synthase Reaction• Condensation of acetyl-CoA and oxaloacetate • The only reaction with C-C bond formation • Rate-limiting step of CAC Mechanism• Uses Acid/Base Catalysis – Carbonyl of oxaloacetate is a good electrophile – Methyl of acetyl-CoA is NOT a good nucleophile but is activated by d ...
... Citrate Synthase Reaction• Condensation of acetyl-CoA and oxaloacetate • The only reaction with C-C bond formation • Rate-limiting step of CAC Mechanism• Uses Acid/Base Catalysis – Carbonyl of oxaloacetate is a good electrophile – Methyl of acetyl-CoA is NOT a good nucleophile but is activated by d ...
Structure and function of haemoglobin: II. Some
... Residues are defined here as invariant when they occur at structurally identical sites in all the normal myoglobins and haemoglobins so far investigated. Abnormal haemoglobins have been excluded, because some of their abnormalities interfere with the oxygen-combining function, so that the protein ca ...
... Residues are defined here as invariant when they occur at structurally identical sites in all the normal myoglobins and haemoglobins so far investigated. Abnormal haemoglobins have been excluded, because some of their abnormalities interfere with the oxygen-combining function, so that the protein ca ...
Coenzyme B 12-Dependent Ribonucleotide Reductase: Evidence
... use a [4Fe-4S] cluster in combination with S-adenosylmethionine and other small molecules to carry out substrate reduction (Eliasson et al., 1992; Reichard, 1993a,b). Despite the differences in quaternary structure, cofactor requirement, as well as primary sequence, evidence suggests that at least t ...
... use a [4Fe-4S] cluster in combination with S-adenosylmethionine and other small molecules to carry out substrate reduction (Eliasson et al., 1992; Reichard, 1993a,b). Despite the differences in quaternary structure, cofactor requirement, as well as primary sequence, evidence suggests that at least t ...
Material acidos, carbonilicos geral
... The Claisen condensation differs from the aldol reaction in several important ways. 1-The aldol reaction may be catalyzed by acid or base, but most Claisen condensation requires base. 2- In contrast to the catalytic base used for aldol reactions, a full equivalent of base (or more) must be used for ...
... The Claisen condensation differs from the aldol reaction in several important ways. 1-The aldol reaction may be catalyzed by acid or base, but most Claisen condensation requires base. 2- In contrast to the catalytic base used for aldol reactions, a full equivalent of base (or more) must be used for ...
Structure, Mechanism, and Disease Implications of Acetyl CoA
... acids in both eukaryotes and prokaryotes. The importance of this enzyme is needed in the initiating reaction for synthesizing fatty acids, which are very important when used as fuel molecules and providing the building blocks of biological membranes. Acetyl-CoA carboxylase catalyzes the committed st ...
... acids in both eukaryotes and prokaryotes. The importance of this enzyme is needed in the initiating reaction for synthesizing fatty acids, which are very important when used as fuel molecules and providing the building blocks of biological membranes. Acetyl-CoA carboxylase catalyzes the committed st ...
Biochemistry
... • Proteolytic active sites are located on the beta subunits – Threonine residue acts as nucleophile to attach carbonyl of peptide bond. ...
... • Proteolytic active sites are located on the beta subunits – Threonine residue acts as nucleophile to attach carbonyl of peptide bond. ...
Restricted rotation of the amino group of nucleic acid base
... gives the shift should be that used for the G-C pair. 650^•H NMR spectra of the 1:1 mixture of 9EA and BrU were measured at three different low (Fig. 2 ) . ...
... gives the shift should be that used for the G-C pair. 650^•H NMR spectra of the 1:1 mixture of 9EA and BrU were measured at three different low (Fig. 2 ) . ...
The evolutionary paths towards complexity: a metabolic perspective
... homologous enzymes belonging to the same fold family, whereas convergent evolution is reserved here to refer to the evolution of identical catalytic functions in nonhomologous enzymes possessing distinct protein folds (Fig. 3). It should be noted that these definitions, using protein fold structure ...
... homologous enzymes belonging to the same fold family, whereas convergent evolution is reserved here to refer to the evolution of identical catalytic functions in nonhomologous enzymes possessing distinct protein folds (Fig. 3). It should be noted that these definitions, using protein fold structure ...
CHEM 331 Problem Set #6
... Native cellulose consists of glucose units linked by (β1à4) glycosidic bonds. The β linkages force the polymer chain into an extended conformation. Parallel series of these extended chains can form intermolecular hydrogen bonds, thus aggregating into long, tough, insoluble fibers. Glycogen consists ...
... Native cellulose consists of glucose units linked by (β1à4) glycosidic bonds. The β linkages force the polymer chain into an extended conformation. Parallel series of these extended chains can form intermolecular hydrogen bonds, thus aggregating into long, tough, insoluble fibers. Glycogen consists ...
Catalytic triad
A catalytic triad refers to the three amino acid residues that function together at the centre of the active site of some hydrolase and transferase enzymes (e.g. proteases, amidases, esterases, acylases, lipases and β-lactamases). An Acid-Base-Nucleophile triad is a common motif for generating a nucleophilic residue for covalent catalysis. The residues form a charge-relay network to polarise and activate the nucleophile, which attacks the substrate, forming a covalent intermediate which is then hydrolysed to regenerate free enzyme. The nucleophile is most commonly a serine or cysteine amino acid, but occasionally threonine. Because enzymes fold into complex three-dimensional structures, the residues of a catalytic triad can be far from each other along the amino-acid sequence (primary structure), however, they are brought close together in the final fold.As well as divergent evolution of function (and even the triad's nucleophile), catalytic triads show some of the best examples of convergent evolution. Chemical constraints on catalysis have led to the same catalytic solution independently evolving in at least 23 separate superfamilies. Their mechanism of action is consequently one of the best studied in biochemistry.