“protein”的概念、定义、翻译、参考文献-科学参考

protein

Chemistry

Any of a large group of organic compounds found in all living organisms. Proteins comprise carbon, hydrogen, oxygen, and nitrogen and most also contain sulphur; molecular weights range from 6000 to several million. Protein molecules consist of one or several long chains (polypeptides) of amino acids linked in a characteristic sequence. This sequence is called the primary structure of the protein. These polypeptides may undergo coiling or pleating, the nature and extent of which is described as the secondary structure. The three-dimensional shape of the coiled or pleated polypeptides is called the tertiary structure. Quaternary structure specifies the structural relationship of the component polypeptides. A great deal of work has been devoted to finding patterns in protein structures.
Proteins may be broadly classified into globular proteins and fibrous proteins. Globular proteins have compact rounded molecules and are usually water-soluble. Of prime importance are the enzymes, proteins that catalyse biochemical reactions. Other globular proteins include the antibodies, which combine with foreign substances in the body; the carrier proteins, such as haemoglobin; the storage proteins (e.g. casein in milk and albumin in egg white), and certain hormones (e.g. insulin). Fibrous proteins are generally insoluble in water and consist of long coiled strands or flat sheets, which confer strength and elasticity. In this category are keratin and collagen. Actin and myosin are the principal fibrous proteins of muscle, the interaction of which brings about muscle contraction. Blood clotting involves the fibrous protein called fibrin.
When heated over 50°C or subjected to strong acids or alkalis, proteins lose their specific tertiary structure and may form insoluble coagulates (e.g. egg white). This usually inactivates their biological properties. In proteins secondary structures, such as alpha helices and beta sheets, often come into contact to form what is called supersecondary structure. The principles of organization of supersecondary structure have been extensively discussed, starting with an investigation by Francis Crick in 1953, before the structure of any protein had been determined. Hydrogen bonds and hydrophobic interactions are very important general features in determining protein folding and protein structure.

Biology

Any of a large group of organic compounds found in all living organisms. Proteins comprise carbon, hydrogen, oxygen, and nitrogen and most also contain sulphur; molecular weights range from 6 to several thousand kilodaltons (kDa). Protein molecules consist of one or several long chains (polypeptides) of amino acids linked via peptide bonds in a characteristic sequence. This sequence is called the primary structure of the protein. These polypeptides may undergo coiling (see alpha helix) or pleating (see beta sheet), the nature and extent of which is described as the secondary structure. The three-dimensional shape of the coiled or pleated polypeptides is called the tertiary structure, the functional unit of which is a domain. Tertiary structure is stabilized by various interactions between the side chains of amino acids that are close together, such as hydrogen bonds and van der Waals forces. Moreover, where two cysteine residues lie together, the sulfhydryl (–SH) groups on their side chains form covalent bonds, or disulphide bridges, linking them together. Quaternary structure specifies the structural relationship of the component polypeptides in proteins that consist of two or more polypeptide chains, such as haemoglobin and collagen. X-ray crystallography is a commonly employed technique to determine the three-dimensional structure of proteins.
Proteins may be globular or fibrous, with various intermediate forms. Globular proteins have compact rounded molecules and are usually water-soluble. Of prime importance are the enzymes, proteins that catalyse biochemical reactions. Other globular proteins include the antibodies, which combine with foreign substances in the body; the carrier proteins, such as haemoglobin; the storage proteins (e.g. casein in milk and albumin in egg white), and certain hormones (e.g. insulin). Cell receptors comprise another group of functionally vital proteins. Fibrous proteins are generally insoluble in water and consist of long coiled strands or flat sheets, which confer strength and elasticity. In this category are keratin and collagen. Actin and myosin are the principal fibrous proteins of muscle, the interaction of which brings about muscle contraction. Blood clotting involves the fibrous protein called fibrin.
When heated over 50°C or subjected to strong acids or alkalis, proteins lose their specific tertiary structure and may form insoluble coagulates (e.g. egg white). This usually inactivates their biological properties.
http://biochemweb.net/proteins.shtml Comprehensive survey of protein biochemistry, from the Virtual Library of Biochemistry, Molecular Biology and Cell Biology

单词	protein
释义	protein Chemistry Any of a large group of organic compounds found in all living organisms. Proteins comprise carbon, hydrogen, oxygen, and nitrogen and most also contain sulphur; molecular weights range from 6000 to several million. Protein molecules consist of one or several long chains (polypeptides) of amino acids linked in a characteristic sequence. This sequence is called the primary structure of the protein. These polypeptides may undergo coiling or pleating, the nature and extent of which is described as the secondary structure. The three-dimensional shape of the coiled or pleated polypeptides is called the tertiary structure. Quaternary structure specifies the structural relationship of the component polypeptides. A great deal of work has been devoted to finding patterns in protein structures. Proteins may be broadly classified into globular proteins and fibrous proteins. Globular proteins have compact rounded molecules and are usually water-soluble. Of prime importance are the enzymes, proteins that catalyse biochemical reactions. Other globular proteins include the antibodies, which combine with foreign substances in the body; the carrier proteins, such as haemoglobin; the storage proteins (e.g. casein in milk and albumin in egg white), and certain hormones (e.g. insulin). Fibrous proteins are generally insoluble in water and consist of long coiled strands or flat sheets, which confer strength and elasticity. In this category are keratin and collagen. Actin and myosin are the principal fibrous proteins of muscle, the interaction of which brings about muscle contraction. Blood clotting involves the fibrous protein called fibrin. When heated over 50°C or subjected to strong acids or alkalis, proteins lose their specific tertiary structure and may form insoluble coagulates (e.g. egg white). This usually inactivates their biological properties. In proteins secondary structures, such as alpha helices and beta sheets, often come into contact to form what is called supersecondary structure. The principles of organization of supersecondary structure have been extensively discussed, starting with an investigation by Francis Crick in 1953, before the structure of any protein had been determined. Hydrogen bonds and hydrophobic interactions are very important general features in determining protein folding and protein structure. Biology Any of a large group of organic compounds found in all living organisms. Proteins comprise carbon, hydrogen, oxygen, and nitrogen and most also contain sulphur; molecular weights range from 6 to several thousand kilodaltons (kDa). Protein molecules consist of one or several long chains (polypeptides) of amino acids linked via peptide bonds in a characteristic sequence. This sequence is called the primary structure of the protein. These polypeptides may undergo coiling (see alpha helix) or pleating (see beta sheet), the nature and extent of which is described as the secondary structure. The three-dimensional shape of the coiled or pleated polypeptides is called the tertiary structure, the functional unit of which is a domain. Tertiary structure is stabilized by various interactions between the side chains of amino acids that are close together, such as hydrogen bonds and van der Waals forces. Moreover, where two cysteine residues lie together, the sulfhydryl (–SH) groups on their side chains form covalent bonds, or disulphide bridges, linking them together. Quaternary structure specifies the structural relationship of the component polypeptides in proteins that consist of two or more polypeptide chains, such as haemoglobin and collagen. X-ray crystallography is a commonly employed technique to determine the three-dimensional structure of proteins. Proteins may be globular or fibrous, with various intermediate forms. Globular proteins have compact rounded molecules and are usually water-soluble. Of prime importance are the enzymes, proteins that catalyse biochemical reactions. Other globular proteins include the antibodies, which combine with foreign substances in the body; the carrier proteins, such as haemoglobin; the storage proteins (e.g. casein in milk and albumin in egg white), and certain hormones (e.g. insulin). Cell receptors comprise another group of functionally vital proteins. Fibrous proteins are generally insoluble in water and consist of long coiled strands or flat sheets, which confer strength and elasticity. In this category are keratin and collagen. Actin and myosin are the principal fibrous proteins of muscle, the interaction of which brings about muscle contraction. Blood clotting involves the fibrous protein called fibrin. When heated over 50°C or subjected to strong acids or alkalis, proteins lose their specific tertiary structure and may form insoluble coagulates (e.g. egg white). This usually inactivates their biological properties. http://biochemweb.net/proteins.shtml Comprehensive survey of protein biochemistry, from the Virtual Library of Biochemistry, Molecular Biology and Cell Biology
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