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peptide, organic compound composed of amino acids linked together chemically by peptide bonds. The peptide bond always involves a single covalent link between the α-carboxyl (oxygen-bearing carbon) of one amino acid and the amino nitrogen of a second amino acid. In the formation of a peptide bond from two amino acids, a molecule of water is eliminated. Small peptides with fewer than about ten constituent amino acids are called oligopeptides, and peptides with more than ten amino acids are termed polypeptides. Compounds with molecular weights of more than 10,000 (50–100 amino acids) are usually termed proteins. Organisms commonly contain appreciable quantities of low-molecular-weight peptides some arising from proteins while others are synthesized directly. Certain of these molecules are unusual in that they incorporate amino acids not found in proteins such as amino acids of the D-configuration. Among the biological peptides are many with physiological or antibacterial activity, such as the peptide hormones oxytocin and vasopressin; adrenocorticotropic hormone (ACTH), secreted by the pituitary gland; and several cyclic peptides, in which the amino-acid sequence forms a ring structure rather than a straight chain, such as the antibiotics tyrocidin and gramicidin. Laboratory synthesis of peptides has risen to the level of a well-defined art in recent years. Synthetic peptides, composed of as many as a hundred amino acids in specified sequence, have been prepared in the laboratory with good purity and high yields.
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A compound that is made up of two or more amino acids joined by covalent bonds which are formed by the elimination of a molecule of H2O from the amino group of one amino acid and the carboxyl group of the next amino acid. Peptides larger than about 50 amino acid residues are usually classified as proteins. Glutathione is the most abundant peptide in mammalian tissue. Hormones such as oxytocin (8), vasopressin (8), glucagon (29), and adrenocorticotropic hormone (39) are peptides whose structures have been deduced; in parentheses are the numbers of amino acid residues for each peptide.

For each step in the biological synthesis of a peptide or protein there is a specific enzyme or enzyme complex that catalyzes each reaction in an ordered fashion along the biosynthetic route. However, it is noteworthy that, although the biological synthesis of proteins is directed by messenger RNA on cellular structures called ribosomes, the biological synthesis of peptides does not require either messenger RNA or ribosomes. See Amino acids, Protein, Ribonucleic acid (RNA), Ribosomes

McGraw-Hill Concise Encyclopedia of Bioscience. © 2002 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



an organic substance consisting of identical or different amino-acid residues joined by peptide bonds. Peptides are classified according to the number of component amino-acid residues as dipeptides, tripeptides, tetrapeptides, and so on, and as polypeptides.

Small quantities of low-molecular-weight peptides occur in nearly all living cells. For example, the tripeptide glutathione is widely distributed in plant and animal tissues, and the dipeptides anserine and carnosine are present in the muscle tissue of vertebrates. Many natural biologically active substances are classified as peptides, including certain hormones (insulin, adrenocortico-trophic hormone, glucagon, vasopressin, oxytocin), antibiotics (gramicidin, bacillin), and angiotensins and kinins, which are present in blood plasma.

The peptide molecule is a linear or branched chain. If the molecule is linear, it has two termini with one terminal amino group (—NH2) and one terminal carboxyl group (—COOH). Peptides with a closed-chain structure are called cyclopeptides, which include many bacterial toxins, hormones, and antibiotics. Many natural peptides contain amino acids that are not present in proteins, for example, D-amino acids. Peptides exhibit amphoteric properties, give biuret (beginning with tripeptides) and ninhydrin reactions, and dissolve readily in water, acids, and alkalies but are practically insoluble in organic solvents. They decompose upon heating to 200°-300°C.

In living cells, peptides are synthesized from amino acids or formed during the enzymatic breakdown of proteins. Chemical synthesis is used to obtain many biologically active natural peptides and their numerous analogues. Advancements in peptide chemistry have resolved many complex problems in modern biochemistry and molecular biology, such as the deciphering of the genetic code.


Khimiia biologicheski aktivnykh prirodnykh soedinenii. Moscow, 1970.


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.


A compound of two or more amino acids joined by peptide bonds.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.


any of a group of compounds consisting of two or more amino acids linked by chemical bonding between their respective carboxyl and amino groups
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
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(17) have reported resistance rates of 5.5%, 7.4% and 41% respectively against metronidazole among Peptostreptococcus spp.
Peptostreptococcus productus###PSP-F###AACTCCGGTGGTATC AGA TG###268 bp
Bacteria morphology Obligate anaerobes Facultative anaerobes Gram-positive cocci Finegoldia Enterococcus Parvimonas Gemella Peptoniphilus Staphylococcus Peptostreptococcus Streptococcus (*) Gram-negative cocci Veillonella Neisseria Actinomyces Eggertella Eubacterium Actinomyces (*) Gram-positive rods Filifactor Corynebacterium Lactobacillus Lactobacillus (*) Olsenella Propionibacterium (*) Propionibacterium Pseudoramibacter Alloprevotella Bacteroides Camphylobacter Dialister Capnocytophaga Gram-negative rods Fretibacterium Eikenella Fusobacterium Haemophilus Porphyromonas Prevotella Tannerella Treponema (*) Some species can also be strict anaerobes.
salivarius 4 IUFD cause cannot Enterococcus species, be determined Peptostreptococcus 5 AFIS S.
coli Klebsiella pneumoniae 33 x [10.sup.3] 15 x [10.sup.3] 3 Peptostreptococcus P.
Antimicrobial, antioxidant, hepatoprotective and antitumor properties of these microorganisms (Actinomyces meyeri, Actinomyces odontolyticus, Bacteroides ovatus, Bifidobacterium bifidum, Bifidobacterium breve, Bifidobacterium dentium, Clostridium butyricum, Clostridium beijerinckii, Enterococcus gallinarum, Enterococcus faecalis, Escherichia coli, Eubacterium aerofaciens, Eubacterium lentum, Lactobacillus spp., Leptotrichia buccalis, Micrococcus spp., Neisseria mucosa, Peptostreptococcus asaccharolyticus, Sarcina spp., Staphylococcus xylosis, Staphylococcus cohni, Staphylococcus capitis, Streptococcus agalactiae) have been only subsequently studied, and each of the strains was assigned a number from No.1 to No.
albicans) --10% Owca (runo) / Bacillus (w tym / Peptostreptococcus spp.
Apart from aerobic bacteria, chronic bacterial prostatitis can be due to anaerobes, with Peptostreptococcus spp.
Cultures of samples taken from ruptured or open HS lesions commonly demonstrate a variety of bacterial species, including Streptococcus viridians, Staphylococcus aureus, Staphylococcus epidermidis, Peptostreptococcus and Bacteroides species, coryneform bacteria, and Gram-negative bacteria, including Escherichia coli and Klebsiella and Proteus species.
El espectro antimicrobiano de los ionoforos puede deducirse del hecho que bacterias productoras de [H.sub.2] y formato (Lachnospira multiparus, Ruminococcus albus y Ruminococcus flavefaciens), de butirato (Butyrivibrio fibrisolvens, Eubacterium cellulosolvens y Eubacterium rumininantium), de lactato (Lactobacillus ruminis, Lactobacillus vitulinus y Streptococcus bovis) y de amoniaco (Clostridium aminophilum, Clostridium sticklandii y Peptostreptococcus anaerobius) son susceptibles a los ionoforos, mientras que bacterias productoras de succinato y propionato (Anaerovibrio lipolytica, Fibrobacter succinogenes, Megasphaera elsdenii, Prevotella ruminicola, Selenomonas ruminantium, Succinimonas amylolytica y Succinivibrio dextrinosolvens) son resistentes (62).