Protein bonds

Calculations were usually carried out under the conditions of a pH-maximum of protein bonding. The experimental results show that the interaction of proteins and most other complex organic substances with CP is accompanied by an increase in the entropy of the system. 

Fig. 16. Isotherms of protein bonding by nonionized CP (a = 0) /) lysozyme — MA-EDMA (2.5 mol%) copolymer 2) haemoglobin — MA-EDMA (2.5mol%) copolymer 3) haemoglobin - AA-EDMA (2.5mol%) copolymer 4) haemoglobin — MA-EDMA (2.5 mol%)gr. copolymer 5) serum albumin — MA-EDMA (2.5 mol%) copolymer. Ceq...

The degree of saturation of carboxylic CP with protein (Y) is determined by the ratio of the amount of protein bonded under these conditions (at a predetermined concentration in solution) to the maximum amount Y = m/M. In this case, Hill s equation becomes... 

As a result of thermodynamic analysis it is shown that protein bonding to carboxylic CP exhibiting a local internal chain structure is determined by the entropy factor, whereas, if the arrangement of flexible chain parts on the protein globule is possible, the energetic component predominates. 

Some properties of Penicillium fellutanum pectinesterase were studied. The optimum of pectinesterase action was detected at pH 5 and 45 °C. The enzyme was stable at pH 4 — 5 and 40 °C (pH 5) for 240 min. and was specific towards lemon pectin. An enzyme preparation composed mainly of pectinesterase was partially purified by gel filtration. Pectinesterase activity was accumulated in one of the obtained fractions. Molecular weights of fraction determined were found to be 46,000 and 1,200. Disk electrophoresis in polyacrilamide gel of the purified preparation revealed two protein bonds with one active component. The partially purified enzyme had the kinetic characteristics =... 

Fournier and DePristo96 calculated bond energies in several small compounds containing disulfide bonds which are known to stabilize the tertiary structure of proteins. Bond dissociation energies are generally overestimated when LDA(SVWN) is used whereas the PW86/P86 functional brings them to within 5 kcal/mol of experimental values. 

Monsan, P., Puzo, G., and Mazarguil, H. (1975) Mechanism of glutaraldehyde-protein bond formation. Biochimie 57, 1281-1292. 

Application of some kind of sample treatment may have the potential to improve substantially the detection of certain antibacterials in milk by microbial routine methods (59). Treatment, for example, of milk samples with ammonium oxalate solution prior to analysis can lead to lower limits of detection of tetracyclines by both microbial inhibition and microbial receptor assays. This is due to the fact that tetracycline residues tend to form chelates with divalent cations and bind to proteins, which reduce their antibacterial efficacy. However, the oxalate treatment causes splitting of complex and/or protein bonds without increasing the detection limits of other antibacterials commonly used in dairy cows. 

The lipid fraction of foods containing the fat-soluble vitamins is composed mainly of triglycerides, with much smaller amounts of sterols, carotenoids, phospholipids, and minor li-poidal constituents. All of these substances exhibit solubility properties similar to those of the fat-soluble vitamins, and therefore they constitute a potential source of interference. A proportion of the indigenous fat-soluble vitamin content of a food is bound up with a lipoprotein complex, and hence the fat-protein bonds must be broken in order to release the vitamin. The protective gelatin coating used in certain proprietary vitamin premixes will need to be dissolved before commencing the analysis of supplemented foods. 

With chiral affinity phases, proteins undergo enantioselective interactions with a great variety of drugs. Thus, the resolution on chiral affinity stationary phases is due to interactions of the enantiomers with proteins bonded to the solid support. Typical proteins used for chiral affinity separa-... 

Improved extractability of gluten proteins from thermally processed food products, due to the formation of carbohydrate-protein bonds, can be attained by using preliminary digestion of samples with glucoamylase or a-amylase (Partridge et al., 2003). However, such modification of analytical tests can cause a change in the properties of allergenic proteins. 

Liberation of Me-Hg from its protein bond by displacing the mercapto group with halogen ion at low pH. 

Crustaceans contain carotenoids bound to protein resulting in a blue or blue-gray color. When the animal is immersed in boiling water, the carotenoid-protein bond is broken and the orange-red color of the free car-... 

In many of the haemoproteins we shall be discussing, the protoporphyrin IX group is held to the polypeptide chain only by hydrogen bonding, Van der Wools forces and iron-protein bonds. In several other cases, notably in cytochrome-c and its related compounds, the haem is covalently linked to the protein via substituents at the pyrrole carbon atoms. Cyto-chrome-c can be regarded as an iron protoporphyrin IX group with the addition of a protein cysteine side-chain across the vinyl double bonds giving two thio-ether links (Fig. 3). 

Cancer pagurus cuticle can be dispersed in hot, aqueous solutions of lithium thiocyanate and be reprecipitated without separating the chitin and protein components. The stability of the complex under these conditions would suggest the presence of primary bonding. Thus, some ehitin-protein bonding does exist in arthropod cuticle, but its exact nature and its physiological significance or its involvement in chitin biosynthesis (or both) remain uncertain. 

Astatine-211 is a promising radionuclide for systemic therapy1 3 due to its decay properties with a half-life of 7.2 hours and an effective emission of one a-particle per decay. However, the weakness of the astatine-protein bond formed after direct astatination1 4 has so far limited its clinical use. To overcome these problems indirect labelling methods have been tried such as the use of ALsuccinimidyl-(trialkylstannyl) benzoate as an intermediate for the astatination of antibodies using conjugation procedures.5 8... 

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