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Methylation often occurs to arginine or lysine and involves adding a methyl group to a nitrogen (replacing a hydrogen). The R groups on these amino acids can be methylated multiple times as long as the bonds to nitrogen does not exceed 4. Methylation reduces the ability of these amino acids to form hydrogen bonds so arginine and lysine that are ...
Iron-binding proteins are carrier proteins and metalloproteins that are important in iron metabolism [1] and the immune response. [2] [3] Iron is required for life.Iron-dependent enzymes catalyze a variety of biochemical reactions and can be divided into three broad classes depending on the structure of their active site: non-heme mono-iron, non-heme diiron , or heme centers. [4]
An individual amino acid in a chain is called a residue, and the linked series of carbon, nitrogen, and oxygen atoms are known as the main chain or protein backbone. [36]: 19 The peptide bond has two resonance forms that confer some double-bond character to the backbone.
The coordination sphere of the calcium ion contains only carboxylate oxygen atoms and no nitrogen atoms. This is consistent with the hard nature of the calcium ion. The protein has two approximately symmetrical domains, separated by a flexible "hinge" region. Binding of calcium causes a conformational change to occur in the protein.
The atoms in a peptide link all lie on the same plane. The nitrogen, hydrogen, and oxygen atoms in a hydrogen bond are approximately in a straight line. The carbon-oxygen and nitrogen-hydrogen groups are all involved in bonding.
Absorption of dietary iron in iron salt form (as in most supplements) varies somewhat according to the body's need for iron, and is usually between 10% and 20% of iron intake. Absorption of iron from animal products, and some plant products, is in the form of heme iron, and is more efficient, allowing absorption of from 15% to 35% of intake.
In this way, measurements of relaxation times can provide information of motions within a molecule on the atomic level. In NMR studies of protein dynamics, the nitrogen-15 isotope is the preferred nucleus to study because its relaxation times are relatively simple to relate to molecular motions. This, however, requires isotope labeling of the ...
Several protein residues can be methylated, most notably the positive groups of lysine and arginine. Arginine residues interact with the nucleic acid phosphate backbone and commonly form hydrogen bonds with the base residues, particularly guanine, in protein–DNA complexes. Lysine residues can be singly, doubly and even triply methylated.