Asparagine hydrolysis

In bacteria (Jackson and Handschumacher, 1970), j8-cyanoalanine hydrolysis and asparagine hydrolysis are carried out by the same enzyme. However, Castric et al. (1972) found no evidence for asparaginase activity in the presence of j3-cyanoalanine hydrolase. It is interesting to note that although j8-cyanoalanine is not a substrate for purified asparaginase from maturing lupin cotyledons, the amino acid is a strong inhibitor (Lea et ai, 1978). 

L-asparaginase, which catalyzes the hydrolysis of L-asparagine to L-aspartate. 

Chiral dienophiles, prepared from an aldehyde and asparagine in water followed by reacting with acryloyl chloride, reacted with cyclopentadiene at room temperature in water or ethanol-water to provide cycloadducts diastereoselectively and chiral products upon separation and hydrolysis (47-64% ee for the endo isomers endo/exo 82 18) (Eq. 12.18).61... 

The answer is b. (Hardman, pp 1268-1269J Asparaginase is an enzyme that catalyzes the hydrolysis of serum asparagine to aspartic acid and ammonia. Major toxicities are related to antigenicity and pancreatitis. In addition, more than 50% of those treated present biochemical evidence of hepatic dysfunction. 

It is noteworthy that there is another limiting factor in the choice of amino acid types at the junction sites which affect the enzymatic process of the intein. For example, in the case of SceVMA (also called PI-Seel) from the IMPACT system, proline, cysteine, asparagine, aspartic acid, and arginine cannot be at the C-terminus of the N-terminal target protein just before the intein sequence. The presence of these residues at this position would either slow down the N-S acyl shift dramatically or lead to immediate hydrolysis of the product from the N-S acyl shift [66]. The compatibility of amino acid types at the proximal sites depends on the specific inteins and needs to be carefully considered during the design of the required expression vectors. The specific amino acid requirements at a particular splicing site depends on the specific intein used and is thus a crucial point in this approach. 

Protein N > % amino acid N + 10 % amino acid N (to include amide N of asparagine and glutamine lost during 6 M HC1 hydrolysis). 

The most important degradation mechanism of asparagine and glutamine residues is formation of an intermediate succinimidyl peptide (6.63) without direct backbone cleavage (Fig. 6.29, Pathway e). The reaction, which occurs only in neutral and alkaline media, begins with a nucleophilic attack of the C-neighboring N-atom at the carbonyl C-atom of the Asn side chain (slow step). The succinimide ring epimerizes easily and opens by hydrolysis (fast step), as shown in Fig. 6.27, to yield the iso-aspartyl peptide (6.64) and the aspartyl peptide (6.65) in a ratio of 3 1. 

Two amino acids—asparagine and glutamine—contain acid-amide groups in the side chains, from which NH3 can be released by hydrolysis (hydrolytic deamination). In the blood, glutamine is the most important transport molecule for amino nitrogen. Hydrolytic deamination of glutamine in the liver also supplies the urea cycle with NH3. 

This enzyme [EC 3.5.1.1] catalyzes the hydrolysis of asparagine to ammonia and aspartate. 

This enzyme [EC 3.2.2.11], also referred to as 1-aspar-tamido-/3-A-acetylglucosamine amidohydrolase, catalyzes the hydrolysis of l-jS-aspartyl-iV-acetylglucosami-nylamine to yield iV-acetylglucosamine and asparagine. 

Aspartic acid.was first obtained by Plisson, in 1827, from asparagine by boiling it with lead hydroxide, and is usually prepared from this compound by hydrolysis with alkali or acid. 

An excellent review on protein hydrolysis for amino acid composition analysis has been published by Eountoulakis and Lahm [190], Hydrolysis can be performed by either chemical (under either acidic or basic conditions) or enzymatic means. The acidic hydrolysis itself can be carried out in a liquid or a gas-phase mode. The conventional acid hydrolysis uses 6M HCl for 20-24 h at 110°C under vacuum [200], In these conditions, asparagine and glutamine are completely hydrolyzed to aspartic acid and glutamic acid, respectively. Tryptophan is completely destroyed (particularly in the presence of high concentrations of carbohydrate), while cysteine and sometimes methionine are partially oxidized. Tyrosine, serine, and threonine are partially destroyed or hydrolyzed and correction factors have to be applied for precise quantification [190,201],... 

Deamidation and imide formation can also negatively influence a protein s biological activity. Deamidation refers to the hydrolysis of the side-chain amide group of asparagine and/or... 

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