{"id":1955,"date":"2024-03-03T17:38:14","date_gmt":"2024-03-03T17:38:14","guid":{"rendered":"https:\/\/cake.appscodestudio.com\/?p=1955"},"modified":"2024-03-03T17:38:16","modified_gmt":"2024-03-03T17:38:16","slug":"general-structure-and-properties-of-proteins","status":"publish","type":"post","link":"https:\/\/cake.appscodestudio.com\/index.php\/2024\/03\/03\/general-structure-and-properties-of-proteins\/","title":{"rendered":"General structure and properties of proteins"},"content":{"rendered":"\n<h2 class=\"wp-block-heading\">The amino acid composition of proteins<\/h2>\n\n\n\n<p>The common property of all proteins is that they consist of long chains of\u00a0\u03b1-amino (alpha amino) acids. The general structure of \u03b1-amino acids is shown in . The \u03b1-amino acids are so called because the \u03b1-carbon\u00a0atom\u00a0in the\u00a0molecule\u00a0carries an amino group (\u2015NH<sub>2<\/sub>); the \u03b1-carbon atom also carries a carboxyl group (\u2015COOH).<img decoding=\"async\" src=\"https:\/\/cdn.britannica.com\/01\/17001-004-27F67347\/Proteins-Formula-1-acids.jpg\" alt=\"Proteins. Formula 1: Generalized structure of all a-amino acids.\"><\/p>\n\n\n\n<p>In acidic solutions, when the pH is less than 4, the \u2015COO groups\u00a0combine\u00a0with hydrogen ions (H<sup>+<\/sup>) and are thus converted into the uncharged form (\u2015COOH). In alkaline solutions, at pH above 9, the ammonium groups (\u2015NH<sup>+<\/sup><sub>3<\/sub>) lose a\u00a0hydrogen ion\u00a0and are converted into amino groups (\u2015NH<sub>2<\/sub>). In the pH range between 4 and 8, amino acids carry both a positive and a negative charge and therefore do not migrate in an electrical field. Such structures have been designated as dipolar\u00a0ions, or zwitterions (i.e., hybrid ions).<\/p>\n\n\n\n<p>Although more than 100 amino acids occur in nature, particularly in plants, only 20 types are commonly found in most proteins. In protein molecules the \u03b1-amino acids are linked to each other by\u00a0peptide\u00a0bonds\u00a0between the amino group of one\u00a0amino acid\u00a0and the carboxyl group of its neighbour.<img decoding=\"async\" src=\"https:\/\/cdn.britannica.com\/00\/17000-004-3C0ADEBE\/Proteins-Formula-peptide-bond.jpg\" alt=\"Proteins. Formula 2: The peptide bond.\"><\/p>\n\n\n\n<p>The\u00a0condensation\u00a0(joining) of three amino acids yields the tripeptide.<img decoding=\"async\" src=\"https:\/\/cdn.britannica.com\/99\/16999-004-857DEA53\/Proteins-Formula-tripeptide-R-groups-possibility.jpg\" alt=\"Proteins. Formula 3: A tripeptide. R' and R&quot; represent the possibility that the three R groups (side chains) could be different.\"><\/p>\n\n\n\n<p>It is customary to write the\u00a0structure of peptides\u00a0in such a way that the free \u03b1-amino group (also called the\u00a0N\u00a0terminus of the peptide) is at the left side and the free carboxyl group (the C terminus) at the right side. Proteins are macromolecular\u00a0polypeptides\u2014i.e., very large molecules (macromolecules) composed of many peptide-bonded amino acids. Most of the common ones contain more than 100 amino acids linked to each other in a long peptide chain. The average\u00a0molecular weight\u00a0(based on the weight of a\u00a0hydrogen\u00a0atom as 1) of each amino acid is approximately 100 to 125; thus, the molecular weights of proteins are usually in the range of 10,000 to 100,000 daltons (one dalton is the weight of one hydrogen atom). The species-specificity and organ-specificity of proteins result from differences in the number and sequences of amino acids. Twenty different amino acids in a chain 100 amino acids long can be arranged in far more than 10<sup>100<\/sup>\u00a0ways (10<sup>100<\/sup>\u00a0is the number one followed by 100 zeroes).<\/p>\n","protected":false},"excerpt":{"rendered":"<p>The amino acid composition of proteins The common property of all proteins is that they consist of long chains of\u00a0\u03b1-amino (alpha amino) acids. The general structure of \u03b1-amino acids is shown in . The \u03b1-amino acids are so called because the \u03b1-carbon\u00a0atom\u00a0in the\u00a0molecule\u00a0carries an amino group (\u2015NH2); the \u03b1-carbon atom also carries a carboxyl group [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5],"tags":[],"class_list":["post-1955","post","type-post","status-publish","format-standard","hentry","category-proteins"],"Cooking_time":"","jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/cake.appscodestudio.com\/index.php\/wp-json\/wp\/v2\/posts\/1955","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/cake.appscodestudio.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/cake.appscodestudio.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/cake.appscodestudio.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/cake.appscodestudio.com\/index.php\/wp-json\/wp\/v2\/comments?post=1955"}],"version-history":[{"count":1,"href":"https:\/\/cake.appscodestudio.com\/index.php\/wp-json\/wp\/v2\/posts\/1955\/revisions"}],"predecessor-version":[{"id":1956,"href":"https:\/\/cake.appscodestudio.com\/index.php\/wp-json\/wp\/v2\/posts\/1955\/revisions\/1956"}],"wp:attachment":[{"href":"https:\/\/cake.appscodestudio.com\/index.php\/wp-json\/wp\/v2\/media?parent=1955"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/cake.appscodestudio.com\/index.php\/wp-json\/wp\/v2\/categories?post=1955"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/cake.appscodestudio.com\/index.php\/wp-json\/wp\/v2\/tags?post=1955"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}