The stages of the peptic hydrolysis of egg albumin

1. Most of the products of the peptic hydrolysis of albumin, about 85 per cent of the total N, are primary in the sense that they arise directly from the protein molecule, and undergo no further hydrolysis. 2. A slow secondary hydrolysis, involving about 15 per cent of the total N, occurs in the proteose and simpler fractions primarily split off. 3. Acid metaprotein in peptic hydrolysis arises as a result of the action of add. It is not an essential stage in the hydrolysis of undenatured albumin. 4. Acid metaprotein is hydrolyzed by pepsin more slowly under comparable conditions than undenatured albumin

Study of Enzymatic Hydrolysis of Dilute Acid Pretreated Coconut Husk

Coconut husk is classified as complex lignocellulosic material that contains cellulose, hemicellulose, lignin, and some other extractive compounds. Cellulose from coconut husk can be used as fermentation substrate after enzymatic hydrolysis. In contrary, lignin content from the coconut husk will act as an inhibitor in this hydrolysis process. Therefore, a pretreatment process is needed to enhance the hydrolysis of cellulose. In this study, the pretreatment was done using dilute sulfuric acid in an autoclave reactor. The pretreatment condition were varied at 80°C, 100°C, 120°C and 0.9%, 1.2%, 1.5% for temperature and acid concentration respectively. The acid pretreated coconut husk was then hydrolyzed using commercial cellulase (celluclast) and β-glucosidase (Novozyme 188). The hydrolysis time is 72 hours and the operating conditions were varied at several temperature and pH. The highest sugar concentration (1.128 g/L) was obtained at pH 4 and 50°C which is pretreated at 100°C using 1.5% acid concentration

The biological synthesis of hippuric acid in vitro

The mechanism of the synthesis of hippuric acid in viva is interesting from several points of view. There is the intrinsic interest in a compound found in the urine of many animals, an interest which is heightened by the use of the rate of hippuric acid excretion following the administration of benzoic acid as a clinical test of liver function. This synthesis is interesting also from the point of view of physiological energetics. The formation of hippuric acid from glycine and benzoic acid is attended by a gain in free energy (Table I). In other words the tendency of the reaction, if allowed to proceed spontaneously at 25° or 38°, is not toward synthesis but toward practically complete hydrolysis of hippuric acid (Table III). Yet when benzoic acid is fed, hippuric acid is rapidly synthesized. This synthesis also occurs and can be measured, as shown below, when liver slices are suspended in Ringer’s solution containing low concentrations of benzoic acid and glycine. More than half the benzoic acid is converted to hippuric acid. From the thermodynamic data it may be deduced that the enzymatic synthesis of hippuric acid cannot be simply the reverse of its hydrolysis. The hydrolysis can proceed spontaneously; the synthesis must be coupled with an energy-yielding reaction

Substrate-Assisted Catalysis Unifies Two Families of Chitinolytic Enzymes

Hen egg-white lysozyme has long been the paradigm for enzymatic glycosyl hydrolysis with retention of configuration, with a protonated carboxylic acid and a deprotonated carboxylate participating in general acid-base catalysis. In marked contrast, the retaining chitin degrading enzymes from glycosyl hydrolase families 18 and 20 all have a single glutamic acid as the catalytic acid but lack a nucleophile on the enzyme. Both families have a catalytic (βα)8-barrel domain in common. X-ray structures of three different chitinolytic enzymes complexed with substrates or inhibitors identify a retaining mechanism involving a protein acid and the carbonyl oxygen atom of the substrate’s C2 N-acetyl group as the nucleophile. These studies unambiguously demonstrate the distortion of the sugar ring toward a sofa conformation, long postulated as being close to that of the transition state in glycosyl hydrolysis.

Modeling the hydrolysis of perfluorinated compounds containing carboxylic and phosphoric acid ester functions, alkyl iodides, and sulfonamide groups

Temperature dependent rate constants were estimated for the acid- and base-catalyzed and neutral hydrolysis reactions of perfluorinated telomer acrylates (FTAcrs) and phosphate esters (FTPEs), and the SN1 and SN2 hydrolysis reactions of fluorotelomer iodides (FTIs). Under some environmental conditions, hydrolysis of monomeric FTAcrs could be rapid (half-lives of several years in marine systems and as low as several days in some landfills) and represent a dominant portion of their overall degradation. Abiotic hydrolysis of monomeric FTAcrs may be a significant contributor to current environmental loadings of fluorotelomer alcohols (FTOHs) and perfluoroalkyl carboxylic acids (PFCAs). Polymeric FTAcrs are expected to be hydrolyzed more slowly, with estimated half-lives in soil and natural waters ranging between several centuries to several millenia absent additional surface area limitations on reactivity. Poor agreement was found between the limited experimental data on FTPE hydrolysis and computational estimates, requiring more detailed experimental data before any further modeling can occur on these compounds or their perfluoroalkyl sulfonamidoethanol phosphate ester (PFSamPE) analogs. FTIs are expected to have hydrolytic half-lives of about 130 days in most natural waters, suggesting they may be contributing to substantial FTOH and PFCA inputs in aquatic systems. Perfluoroalkyl sulfonamides (PFSams) appear unlikely to undergo abiotic hydrolysis at the S-N, C-S, or N-C linkages under environmentally relevant conditions, although potentially facile S-N hydrolysis via intramolecular catalysis by ethanol and acetic acid amide substituents warrants further investigation

Glucose Content of Sago Waste After Chloride Acid Pre- Treatment Hydrolysis For Bioethanol Production

Indonesia is a country with abundant agricultural biological resources. One of the plants as a biological source is sago. Sago processing wastes such as bark and waste about 72%. Jepara district has rich sago waste, piled on the side of the road and the river so it is very disturbing. In generally, sago industrial wastes utilization is still lacking, especially as a source of energy. Sago waste consists mainly of cellulose and has the potential to be processed into bioethanol. Glucose contained in cellulosic biomass is the main ingredient in the manufacture of bioethanol and need to know the glucose content after of sago waste cellulose hydrolysis process to determine the highest amount of ethanol. This study aims to determine the glucose content of sago wastewater using acid catalysis with different concentrations of the hydrolysis process, and to know the appropriate concentration of acid to produce the highest glucose and bioethanol in all type of waste. The result showed that type of waste had no effect on glucose content. Glucose content of sago waste showed no difference between the effect of chlorida acid concentration with glucose content. However, hydrolysis at concentration tends to produce the highest glucose

Supported Co catalysts prepared as thin films by magnetron sputtering for sodium borohydride and ammonia borane hydrolysis

Supported Co catalysts were prepared for sodium borohydride and ammonia borane hydrolysis by magnetron sputtering for the first time under different conditions. Ni foam was selected as support. Deposition conditions (time, pressure, and power) were varied to improve catalytic activity. A decrease in deposition power from 200 to 50 W, leads to a decrease in crystallite and column size and a higher activity of catalysts. The increase in deposition pressure from 1.5 × 10−2 to 4.5 × 10−2 mbar produces same effect but in this case the enhancement in activity is higher because amorphous materials were obtained. The highest activity for SB hydrolysis was 2650 ml min−1 gcat−1 for the 50 W Co 4.5 (4 h) sample (Ea = 60 ± 2 kJ mol−1). For AB hydrolysis activity for the 50 W Co 3.2 (4 h) sample was similar. Durability of the thin films was tested for both reactions upon cycling (14 cycles). Diluted acid washing was effective to recover the activity for sodium borohydride reaction but not for ammonia borane hydrolysis. The strong Co–NH3 interactions explain the non-efficiency of the acid washing

The hydrolysis of proteins

Temperature effects on hydrolysis reaction in protein amino acid

Beef hydrolysis by Zyactinase™ enzymes : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy at Massey University, Auckland, New Zealand.

Protein hydrolysis is the term that applies to all possible ways of splitting proteins to produce products with lower molecular weight. There is a continuous search for novel products derived from waste materials. In the developed nations considerable amount of meat off-cuts are discarded each year. Utilizing these leftovers by developing new technology for protein recovery and modification and production of a broad spectrum of food ingredients greatly enhances its final value. The aim of this research was to partially hydrolyse beef meat protein with a commercial kiwifruit product called ZyactinaseTM, which is essentially freeze-dried kiwifruit to determine the effect of various processing conditions that influence the extent of beef meat hydrolysis. Secondly to determine the peptide and amino acid profile of the beef meat sample after hydrolysis. Thirdly to determine the relative reaction of ZyactinaseTM on various beef meat protein fractions. This study also aimed to evaluate the rate and the extent of partial enzymic hydrolysis of lean beef using ZyactinaseTM enzymes in order to obtain a better understanding of protein hydrolysis reaction. Lean beef minced was partially hydrolysed using the Zyactinase enzymes for different processing times (up to 360 minutes), temperatures (27°C to 70°C) and varying enzyme concentrations. No pH adjustment on the raw material was carried out except for pH studies. The hydrolysates were collected and analysed for total nitrogen content and degree of hydrolysis. The method used to characterize the extent of protein hydrolysis was SN-TCA index (fraction of nitrogen soluble in trichloroacetic acid) also called non-protein nitrogen NPN. Peptide and amino acid in protein hydrolysates were analysed by HPLC and different protein fractions in the hydrolysates were characterised by SDS-PAGE. The relationship between the reaction temperature, enzyme concentration and processing time to the total nitrogen and NPN were determined. The total nitrogen content remained relatively constant throughout the hydrolysis process. In addition, the NPN content increased as the temperature, processing time and enzyme concentration increased. The optimum pH range for the enzyme’s activity was 4 – 5.6 and optimum temperature was 60°C. Furthermore, most of the higher molecular weight protein bands on SDS- PAGE disappeared after hydrolysis and lower molecular weight protein bands increased in intensity. Zyactinase was also found to digest protein in the myobrilla and sarcoplasmic meat fractions at similar rates as whole beef meat. The results provide basic understanding of the kiwifruit enzymes action toward protein that may lead to improved methods for recovering meat protein or developing new food materials

Estimated carboxylic acid ester hydrolysis rate constants for food and beverage aroma compounds

Aroma compounds in the Flavornet database were screened for potentially hydrolyzable carboxylic acid ester functionalities. Of the 738 aroma compounds listed in this database, 140 molecules contain carboxylic acid ester groups that may be amenable to hydrolysis in various food and beverage products. Acid- (k~A~) and base- (k~B~) catalyzed and neutral (k~N~) hydrolysis rate constants in pure water at 25°C were estimated for these aroma compounds. Where available, good agreement between theoretical and experimental hydrolytic half-lives was obtained at various pH values. Wide ranges and broad frequency distributions for k~A~, k~B~, and k~N~ are expected among the various hydrolyzable aroma compounds, with estimated k~A~ ranging from 3.7×10^-8^ to 4.7×10^-4^ M^-1^ s^-1^, estimated k~B~ ranging from 4.3×10^-4^ to 43 M^-1^ s^-1^, and estimated k~N~ ranging from 4.2×10^-17^ to 7.6×10^-9^ M^-1^ s^-1^. The resulting hydrolytic half-lives also range widely, from 10 days to 370 years at pH 2.8, 18 days to 4,900 years at pH 4.0, 1.8 days to 470 years at pH 7.0, and 26 minutes to 5.1 years at pH 9.0. The findings presented herein attest to the importance of considering abiotic hydrolysis and matrix pH when modeling the evolution of sensory characteristics for foods and beverages with carboxylic acid ester based aroma compounds