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As a fuel, proteins provide as much energy density as carbohydrates: 17 kJ (4 kcal) per gram; in contrast, lipids provide 37 kJ (9 kcal) per gram. The most important aspect and defining characteristic of protein from a nutritional standpoint is its amino acid composition. [2] Proteins are polymer chains made of amino acids linked together by ...
Compared to the study of protein–protein and protein–DNA interaction, it is relatively recent that scientists get to know the protein–carbohydrate binding. [1] Many of these interactions involved carbohydrates found at the cell surface, as part of a membrane glycoprotein or glycolipid. These interactions can play a role in cellular ...
Each protein has its own unique amino acid sequence that is specified by the nucleotide sequence of the gene encoding this protein. The genetic code is a set of three-nucleotide sets called codons and each three-nucleotide combination designates an amino acid, for example AUG ( adenine – uracil – guanine ) is the code for methionine .
Modified amino acids are sometimes observed in proteins; this is usually the result of enzymatic modification after translation (protein synthesis). For example, phosphorylation of serine by kinases and dephosphorylation by phosphatases is an important control mechanism in the cell cycle. Only two amino acids other than the standard twenty are ...
Lectins, or proteins that bind carbohydrates, can recognize specific oligosaccharides and provide useful information for cell recognition based on oligosaccharide binding. [citation needed] An important example of oligosaccharide cell recognition is the role of glycolipids in determining blood types.
At the top level are all alpha proteins (domains consisting of alpha helices), all beta proteins (domains consisting of beta sheets), and mixed alpha helix/beta sheet proteins. While most proteins adopt a single stable fold, a few proteins can rapidly interconvert between one or more folds. These are referred to as metamorphic proteins. [5]
Lactose is a disaccharide found in animal milk. It consists of a molecule of D-galactose and a molecule of D-glucose bonded by beta-1-4 glycosidic linkage.. A carbohydrate (/ ˌ k ɑːr b oʊ ˈ h aɪ d r eɪ t /) is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water) and thus with the empirical formula C m ...
Generally, the carbohydrate part(s) play an integral role in the function of a glycoconjugate; prominent examples of this are neural cell adhesion molecule (NCAM) and blood proteins where fine details in the carbohydrate structure determine cell binding (or not) or lifetime in circulation.