Our Name Is a Peptide: U-K-M-A-S-T-E-R-P-E-P-T-I-D-E-S

The sequence, letter by letter

Position	Letter	Amino acid	Three-letter code	Worth knowing
1	U	Selenocysteine	Sec	The 21st amino acid (see below)
2	K	Lysine	Lys	Essential: the body can't make it
3	M	Methionine	Met	Starts almost every protein a cell makes
4	A	Alanine	Ala
5	S	Serine	Ser
6	T	Threonine	Thr	Essential
7	E	Glutamic acid	Glu
8	R	Arginine	Arg
9	P	Proline	Pro	The only standard amino acid whose side chain loops back to its own backbone nitrogen
10	E	Glutamic acid	Glu
11	P	Proline	Pro
12	T	Threonine	Thr	Essential
13	I	Isoleucine	Ile	Essential
14	D	Aspartic acid	Asp
15	E	Glutamic acid	Glu
16	S	Serine	Ser

In three-letter code: Sec-Lys-Met-Ala-Ser-Thr-Glu-Arg-Pro-Glu-Pro-Thr-Ile-Asp-Glu-Ser.

By convention a sequence is written from the amino end (the N-terminus) on the left to the carboxyl end (the C-terminus) on the right, so our name starts with a free amino group on the U and ends with a free carboxyl group on the final S. Eleven different amino acids make up the sixteen positions: glutamic acid appears three times; proline, serine and threonine twice each; the rest once. Five of the sixteen residues are essential amino acids, the ones people have to get from food: lysine, methionine, isoleucine and threonine (twice).

All the one-letter and three-letter codes

The name only works because of U

Every letter in our name except the first belongs to the twenty standard amino acids. U is the code for selenocysteine, often called the 21st amino acid, and without it the name couldn't be spelt.

Selenocysteine is cysteine with selenium in place of sulfur. Cells build it into proteins in an unusual way: it is coded by UGA, a codon that normally means "stop", and a folded structure in the messenger RNA, called a SECIS element, tells the cell to read that UGA as selenocysteine instead. A 2003 study of mammalian genomes found that humans make 25 proteins containing it (Kryukov and colleagues, Science, 2003).

That one selenium atom also leaves a fingerprint. Selenium has six stable isotopes, so a mass spectrum of our name would show a cluster of peaks rather than one dominant peak.

What the name weighs

Calculated from the sequence, with free ends:

Property	Value
Length	16 residues
Formula	C72H120N20O29SSe
Monoisotopic mass	1840.7416 Da (using selenium-80, its most abundant isotope)
Average molecular weight	1840.86 g/mol
[M+H]+	1841.7489
[M+2H]2+	921.3781

The single sulfur comes from methionine and the single selenium from selenocysteine. You can check every number with our peptide mass calculator, which opens with our name already typed in.

The logo

Our logo shows the start of the chain: U for selenocysteine, K for lysine and M for methionine, joined by peptide bonds. Methionine is the amino acid that starts almost every protein a cell makes, so M is the bead we mark in lime.

Why "Master"

Master is the standard we set ourselves: to know each product down to its sequence, and each shipment down to its last document. That's why every batch we supply comes with its certificate, and why batch numbers and expiry dates appear on every packing list and delivery note. Quality and documentation

Our Arabic name

Our Arabic name, ماستر البريطانية للببتايد, carries the same promise in the language of the region we serve.

Questions people ask about the name

Is U-K-M-A-S-T-E-R-P-E-P-T-I-D-E-S a real peptide?: It's a valid sequence, and selenocysteine peptides can be made by solid-phase synthesis using protected selenocysteine building blocks. But it isn't a product: it's a name.
What is the one-letter code for selenocysteine?: U. Its three-letter code is Sec. It sits alongside the twenty standard letters in the IUPAC-IUB amino acid codes.
What does UKMP stand for?: UK Master Peptides. More about us
Can other words be spelt in amino acids?: Plenty, as long as they avoid the letters that don't stand for an amino acid. If you want to try, start with what is a peptide and the code table.

Every letter of our name is an amino acid