1) Essential amino acid 2) Essential amino acid 3) Sulfur amino acid 
Methionine (n or n; abbreviated as Met or M) is an α-amino acid with the chemical formula HO2CCH(NH2)CH2CH2SCH3. This essential amino acid is classified as nonpolar. This amino-acid is coded by the initiation codon AUG which indicates mRNA`s coding region where translation into protein begins. ==Function== Together with cysteine, methionine is o....
sulfur-containing amino acid obtained by the hydrolysis of most common proteins. First isolated from casein (1922), methionine accounts for about 5 ... [7 related articles]
<biochemistry> Contains the SCH3 group that can act as a methyl donor (see S adenosyl methionine). Common in proteins but at low frequency. The met x linkage is subject to specific cleavage by cyanogen bromide. ... See: formyl peptides. ... (18 Nov 1997) ... 
(mә-thi´o-nēn) a sulfur-containing essential amino acid that furnishes both methyl groups and sulfur necessary for metabolism.
see s-adenosylmethionine.
(= met; M; 149D) Contains the -SCH3 group that can act as a methyl donor (see S-adenosyl methionine). Common in proteins but at low frequency. The met-x linkage is subject to specific cleavage by cyanogen bromide. See also formyl peptides, and Table A2.
(Met, M) Type: Term Pronunciation: me-thī′ō-nēn Definitions: 1. The l-isomer is a nutritionally essential amino acid and the most important natural source of 'active methyl' groups in the body, hence usually involved in methylations in vivo; the dl-form is used as an adjunct in the treatment of liver diseases. ...
Methionine: An amino acid, one of the 20 building blocks of protein. A dietary essential amino acid, methionine provides methyl groups and sulfur for normal metabolism. Symbol: Met.
[n] - a crystalline amino acid containing sulfur
An essential amino acid
noun a crystalline amino acid containing sulfur; found in most proteins and essential for nutrition