Debate and discussion of any biological questions not pertaining to a particular topic.
5 posts • Page 1 of 1
I'm a student from china and i would like to know if there is any law in naming them? As names of alkanes i can find out they usually end in -ane and the head words can represent the number of carbon atoms , hex means 6 and so on.
Unfortunately, the only law here is the suffix -ine, which is used in most of old nomenclature (like pepsine, leucine etc.; with three exceptions as Tryptophan and the acidic AAs).
The only way to memorize them is just drill, but I will give you a hint, which our prof gave us. Look on the amino acids as on derivatives of alanine, instead of glycine.
Glycine is of course an exception. Proline as well, since it is an imino acid.
Alanine is the "basic" amino acid.
Now, serine and cysteine are hydroxy- and thiol derivatives.
Valine and leucine are dimethyl and isopropyl derivatives. Isoleucine is not iso- for no reason, so you move the methyl by one carbon.
Threonine and methionine are little bit tricky to remember, but simply they are methyl-hydroxyl and thioether derivatives.
The aromatic amino acids are quite simple, since you just add benzene to the Ala and you have (surprisingly ) phenylalanine; just add hydroxyl and you get tyrosine. Add imidazole and you get histidine. With the largest system you get tryptophan
For the acidic AAs, just add carboxyl to Ala and you get aspartic acid. Since Glutamic acid is later in alphabet, it is longer by one carbon. The amides are just likewise.
The basic AAs (hey, how stupid is the English, since it calls basic and basic with the same word, isn't it? ) are little complicated. Just remember, that lysine has epsilon-NH2, it is often used for binding, modifications etc. Thus it must have alpha-carbon (the one between NH2 and COOH), beta, gamma, delta and epsilon and then there is the other NH2. Arginine is a little tough, probably easiest way is to remember it is one carbon shoter than Lys and there is the guanidium group. If you look on the urea cycle, you can see there is the arginine as well as ornithin, which is one-carbon-shorter homologue of lysine.
If you want to learn the one letter code, look on the IUBMB page. It explained in there (below the table) and it's quite logic. Especially, if you type Fenylalanin in your language
Cis or trans? That's what matters.
Proteins linear polymers built of amino acids. The sequence of the amino acids decide the three dimensional fold of the protein. The sequence of amino acid also defines the flexibility or rigidity of an protein. This structural property crucial to the protein functions. There are 20 commonly occurring amino acids in nature. A protein can contain any combination and number of the these 20 amino acids.
Proteins contain a wide range of functional groups such as thiols, alcohols, Carboxamides and many more. The chemical activity of these functional groups is essential for the function of proteins.
5 posts • Page 1 of 1
Who is online
Users browsing this forum: No registered users and 8 guests