Peptide Biosynthesis, Nucleic Acid-Independent: The enzymatic synthesis of PEPTIDES without an RNA template by processes that do not use the ribosomal apparatus (RIBOSOMES).Peptide Biosynthesis: The production of PEPTIDES or PROTEINS by the constituents of a living organism. The biosynthesis of proteins on RIBOSOMES following an RNA template is termed translation (TRANSLATION, GENETIC). There are other, non-ribosomal peptide biosynthesis (PEPTIDE BIOSYNTHESIS, NUCLEIC ACID-INDEPENDENT) mechanisms carried out by PEPTIDE SYNTHASES and PEPTIDYLTRANSFERASES. Further modifications of peptide chains yield functional peptide and protein molecules.Peptide Synthases: Ligases that catalyze the joining of adjacent AMINO ACIDS by the formation of carbon-nitrogen bonds between their carboxylic acid groups and amine groups.Peptides: Members of the class of compounds composed of AMINO ACIDS joined together by peptide bonds between adjacent amino acids into linear, branched or cyclical structures. OLIGOPEPTIDES are composed of approximately 2-12 amino acids. Polypeptides are composed of approximately 13 or more amino acids. PROTEINS are linear polypeptides that are normally synthesized on RIBOSOMES.Peptide Nucleic Acids: DNA analogs containing neutral amide backbone linkages composed of aminoethyl glycine units instead of the usual phosphodiester linkage of deoxyribose groups. Peptide nucleic acids have high biological stability and higher affinity for complementary DNA or RNA sequences than analogous DNA oligomers.Peptide Fragments: Partial proteins formed by partial hydrolysis of complete proteins or generated through PROTEIN ENGINEERING techniques.Molecular Sequence Data: Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.Amino Acid Sequence: The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.Peptide Library: A collection of cloned peptides, or chemically synthesized peptides, frequently consisting of all possible combinations of amino acids making up an n-amino acid peptide.Nucleic Acid Conformation: The spatial arrangement of the atoms of a nucleic acid or polynucleotide that results in its characteristic 3-dimensional shape.Nucleic Acid Probes: Nucleic acid which complements a specific mRNA or DNA molecule, or fragment thereof; used for hybridization studies in order to identify microorganisms and for genetic studies.Base Sequence: The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.Antimicrobial Cationic Peptides: Small cationic peptides that are an important component, in most species, of early innate and induced defenses against invading microbes. In animals they are found on mucosal surfaces, within phagocytic granules, and on the surface of the body. They are also found in insects and plants. Among others, this group includes the DEFENSINS, protegrins, tachyplesins, and thionins. They displace DIVALENT CATIONS from phosphate groups of MEMBRANE LIPIDS leading to disruption of the membrane.Peptides, Cyclic: Peptides whose amino and carboxy ends are linked together with a peptide bond forming a circular chain. Some of them are ANTI-INFECTIVE AGENTS. Some of them are biosynthesized non-ribosomally (PEPTIDE BIOSYNTHESIS, NON-RIBOSOMAL).Nucleic Acid Amplification Techniques: Laboratory techniques that involve the in-vitro synthesis of many copies of DNA or RNA from one original template.