aevorti.blogg.se - Positively charged amino acids

-OH group: serine (Ser, S), threonine (Thr, T) and tyrosine (Tyr, Y).

-NH 2 group: asparagine (Asn, N) and glutamine (Gln, Q).

In the side chains of the other 5 amino acids (N, Q, S, T, Y), the atomes are uncharged (the atoms belong to polar, but uncharged, -NH2 or -OH groups):.

can be engaged in ionic bonds (through electrostatic attraction).

are hydrophilic (or neutral, for histidine) and nearly always found on the outside of proteins.

basic: histidine (His, H), lysine (Lys, K) and arginine (Arg, R).

acidic: aspartic acid (Asp, D) and glutamic acid (Glu, E).

In the side chains of the first 5 amino acids (D, E, H, K, R), the atoms are charged.

There are 10 polar amino acids (same amino acids as in Table 3, except tryptophan usually nonpolar): D, E, H, K, R, N, Q, S, T, Y, that fall into 2 categories: Polarity of the amino acid side chains Amino acid side chains with hydrogen donor and/or acceptor atoms are polar

9 amino acids (alanine, cysteine, glycine, isoleucine, leucine, methionine, phenylalanine, proline, valine) have no hydrogen donor or acceptor atoms in their side chains.

b Between parentheses, number of hydrogen bonds that an acceptor atom can accept, if more than one.

Amino acidsĪ Between parentheses, number of "sp hydrogens" that a donor atom can donate, if more than one. Table 3: Hydrogen donor and acceptor atoms in amino acid side chains. 6 amino acids (asparagine, glutamine, histidine, serine, threonine and tyrosine) have both hydrogen donor.2 amino acids (aspartic acid, glutamic acid) have hydrogen acceptor atoms in their side chain.3 amino acids (arginine, lysine and tryptophan) have hydrogen donor atoms in their side chains.Hydrogen donor and acceptor atoms of the amino acid side chainsĬlick here for Amino acid atoms nomenclature. They are: A, N, C, Q, G, I, L, M, F, P, S, T, W, Y, V. The pK of the side chain group is the pH at which exactly half of a carboxylicįifteen AA have uncharged side chains. Table 1: pK of the amino acid side chain group. Side chains accept an H + ion (proton) and are Positive charged (basic side chains): lysine, arginine and histidineĪt a pH superior to their pK (Table 2), the amine side chains are uncharged.Īt a pH inferior to their pK, the lysine, arginine and histidine.They are therefore acid.Īt a pH inferior to their pK, the aspartic acid and glutamic acid side chains are uncharged. Negative charged (acidic side chains): aspartic acid and glutamic acidĪt a pH superior to their pK (Table 2), the carboxylicĪnd are negative charged.The charge on the amino acid side chain depends on the pK of the AA (Table 1) and on the pH of the solution.

( acidic side chains), and three are positive charged: At pH=7, two are negative charged:Īspartic acid (Asp, D) and glutamic acid (Glu, E) When an amino acid (AA) is incorporated into a polypeptide, the charges on the amino and carboxyl groups disappear.Īmong the 20 common amino acids, five have a sideĬhain which can be charged. Hydrogen donor and acceptor atoms of the amino acid side chainsĬharge of the amino acid side chains Charged side chains.Formula of the 20 common amino acids and structural details of the side chainsĬharge, hydrogen donor and acceptor atoms, and polarity of the amino acid side chains.Amino acid abbreviations, characteristics, volume and hydropathy index.IMGT classes of the 20 common amino acids.