New Comprehensive Biochemistry 

About: New Comprehensive Biochemistry is an academic journal. The journal publishes majorly in the area(s): Glycoprotein & Gene. It has an ISSN identifier of 0167-7306. Over the lifetime, 597 publications have been published receiving 9775 citations.

Chapter 7 Microbial peptidoglycan (murein) hydrolases

Abstract: Publisher Summary This chapter discusses the microbial peptidoglycan (murein) hydrolases. Studies of the action of lysozyme and of other bacteriolytic enzymes revealed that the bacteriolytic action was a result of hydrolysis of specific bonds in the protective and shape-maintaining bacterial exoskeleton, the peptidoglycan (murein) sacculus of the cell wall. The observations that bacteriolysis could be prevented, with the formation of spherical, osmotically fragile bodies, by the provisions of an iso-osmotic environment again demonstrated that autolysis was the result of hydrolysis of a sufficient number of bonds in the protective cell wall peptidoglycan to cause its dissolution and removal from the bacterial surface. The peptide moieties of peptidoglycan are attacked by exo- as well as by endo-peptidases. DD-carboxypeptidases convert pentapeptide into tetrapeptide moieties by cleaving the terminal D-aIanyl-D-alanine bond of crosslinked and uncrosslinked stem peptides. DD-endopeptidases have been described and isolated which cleave the crucial DD-peptide bond that crosslinks the stem peptides to yield the characteristic peptidoglycan network.

Chapter 9 Mechanism of bile acid biosynthesis in mammalian liver

Abstract: Publisher Summary This chapter discusses the mechanism of bile-acid biosynthesis in mammalian liver. Generally, the most important pathway for the metabolism and excretion of cholesterol in mammals is the formation of bile acids. The major primary bile acids, cholic and chenodeoxycholic acid, are formed from cholesterol in the liver and secreted with bile to the intestine. The reactions involved are saturation of the double bond, epimerization of the 3β-hydroxyl group, introduction of hydroxyl groups into the 7α and 12α positions, oxidation of the C27, side chain to a C24-carboxylic acid, and conjugation with taurine or glycine. The sequence of these reactions has been studied extensively and the major pathways have been defined with a high degree of certainty in rat and man. After the secretion of the primary bile acids with bile to the intestine, microorganisms may transform them into secondary bile acids, such as deoxycholic and lithocholic acid. The major part of all bile acids in the intestine is absorbed and returns to the liver via the portal blood. Only a small fraction is excreted in the feces. The bile acids returning to the liver in the enterohepatic circulation may be further metabolized before they are reconjugated and re-excreted into the bile. The conversion of cholesterol into bile acids represents the most obvious example of the high capacity of the liver to convert lipid-soluble material into excretable water-soluble products.

Chapter 14 Lipoproteins, structure, function, biosynthesis and model for protein export

Abstract: Publisher Summary This chapter discusses the lipoproteins, structure, function, biosynthesis, and model for protein export. Murein lipoprotein of Escherichia coli was, apart from the basic myelin protein, the first integral membrane protein for which the primary structure was determined. It was the first protein in which a covalently bound lipid was demonstrated by determination of the structure of the lipid and its mode of attachment to the protein. The mature murein lipoprotein consists of 58 amino acid residues, in which no glycine, histidine, proline, phenylalanine, and tryptophan is present. The amino acid residues of murein lipoprotein are arranged such that all charged and hydrophilic side chains are located at one side, and all hydrophobic side chains at the opposing side of α-helix. Indeed, an α -helical content of over 80% was determined by circular dichroism measurements of lipoprotein samples isolated by using boiling sodium dodecyl sulfate, and can be done by employing a much milder procedure as well.

Chapter 4 - An introduction to hidden Markov models for biological sequences

Abstract: This chapter discusses the hidden Markov models (HMM) for biological sequences. A hidden Markov model (HMM) is a statistical model, which is very well suited for many tasks in molecular biology, although they have been mostly developed for speech recognition. The most popular use of the HMM in molecular biology is as a probabilistic profile of a protein family, which is called a profile HMM. From a family of proteins (or DNA), a profile HMM can be made for searching a database for other members of the family. These profile HMMs resemble the profile and weight matrix methods, and the main contribution is that the profile HMM treats gaps in a systematic way. The HMM is particularly well suited for problems with a simple grammatical structure, such as gene finding. In gene finding several signals must be recognized and combined into a prediction of exons and introns and the prediction must conform to various rules to make it a reasonable gene prediction. An HMM can combine recognition of the signals and it can be made such that the predictions always follow the rules of a gene.