Metabolic

Amylin

Human islet amyloid polypeptide

37 residues · 3903 Da · 273 atoms

Thirty-seven residues with a small disulfide ring at the front. Pramlintide, also in this library, is this molecule with three prolines substituted in to stop it aggregating, and the two are worth reading together.

Reference entry · not stocked

Apelin-13

13 residues · 1534 Da · 108 atoms

Thirteen residues opening with a pyroglutamate ring, which is drawn. The pyroglutamate form is the one that circulates; without it the peptide is cleared far faster.

Reference entry · not stocked

Apelin-17

17 residues · 2139 Da · 151 atoms

Seventeen residues, four longer than apelin-13 at the front and strongly basic there. Both are here, so the extra stretch can be seen.

Reference entry · not stocked

Exenatide

39 residues · 4187 Da · 295 atoms

Thirty-nine residues ending in an amide. Originally isolated from the saliva of the Gila monster, and the reason it resists the enzyme that clears the human hormone is the glycine at position two.

Reference entry · not stocked

GLP-1 (7-36)

The active fragment of glucagon-like peptide 1

30 residues · 3298 Da · 234 atoms

Thirty residues, the fragment of GLP-1 that is actually active. Every long-acting analogue of it is a modification of this chain, which is why it is worth having the original to compare against.

Reference entry · not stocked

GLP-2

33 residues · 3766 Da · 265 atoms

Thirty-three residues, cut from the same precursor protein as GLP-1 but acting on the gut lining rather than on insulin release.

Reference entry · not stocked

Glucagon

29 residues · 3483 Da · 246 atoms

Twenty-nine residues, free acid at the C-terminus rather than the amide most of this family carries. The natural counterpart to insulin.

Reference entry · not stocked

Guanylin

15 residues · 1459 Da · 98 atoms

Fifteen residues with two disulfides that cross rather than nest, which is the opposite arrangement to the conotoxins here. Four cysteines out of fifteen residues.

Reference entry · not stocked

HGH Fragment 176-191

C-terminal fragment of growth hormone

16 residues · 1817 Da · 126 atoms

Sixteen residues from the tail end of human growth hormone. Two cysteines are present; in the parent protein they form a disulfide, and this model draws them free because the isolated fragment is usually handled in reduced form.

Reference entry · not stocked

Linaclotide

14 residues · 1527 Da · 101 atoms

Fourteen residues with six cysteines, so nearly half the chain is bonded to another part of it. Two cysteines sit side by side at the very front and bond to different partners.

Reference entry · not stocked

Melanin concentrating hormone

19 residues · 2387 Da · 165 atoms

Nineteen residues with a disulfide closing a ring of nine in the middle, leaving a short tail free at each end.

Reference entry · not stocked

Obestatin

23 residues · 2547 Da · 181 atoms

Twenty-three residues cut from the same precursor as ghrelin, from the stretch immediately after it. Named for what it was first reported to do, which later work did not settle.

Reference entry · not stocked

Pancreatic polypeptide

36 residues · 4182 Da · 294 atoms

Thirty-six residues, exactly the same length as peptide YY and built to the same plan, though it shares fewer than half its positions. Both are here, so how much can change while the shape holds is visible directly.

Reference entry · not stocked

Peptide YY

36 residues · 4310 Da · 306 atoms

Thirty-six residues named for the tyrosine at each end, which is what the two Ys stand for. A gut hormone released after eating, and the only member of its family in the library that starts and ends the same way.

Reference entry · not stocked

Peptide YY (3-36)

34 residues · 4050 Da · 287 atoms

Thirty-four residues sharing the fold of neuropeptide Y, which is also here: a proline-rich front end folding back against a long helix. The 3-36 form is the one that circulates after a meal.

Reference entry · not stocked

PepX-3 RT

Triple incretin receptor agonist

39 residues · 4076 Da · 289 atoms

A 39-residue lipopeptide studied as a GLP-1 / GIP / glucagon receptor triple agonist. Two positions carry Aib (2 and 20) and one carries alpha-methyl-leucine (13) - all three are modelled. The C20 fatty diacid on Lys17 is a lipid tail and is not drawn, so the mass shown is the peptide backbone only.

In our catalogue

Plecanatide

Uroguanylin with one substitution

16 residues · 1682 Da · 113 atoms

Sixteen residues, differing from uroguanylin at a single position. Putting the two side by side shows how small a change is enough to matter.

Reference entry · not stocked

Pramlintide

Amylin analogue closed by a disulfide

37 residues · 3949 Da · 277 atoms

Thirty-seven residues with cysteines at two and seven joined by a disulfide, closing a small ring at the N-terminal end while the rest of the chain runs free. Three prolines distinguish it from human amylin.

Reference entry · not stocked

Teduglutide

GLP-2 with a single substitution

33 residues · 3752 Da · 264 atoms

GLP-2 with the alanine at position two replaced by glycine. One residue, and it is the difference between something cleared in minutes and something that lasts hours, because that position is where the enzyme cuts.

Reference entry · not stocked

Uroguanylin

16 residues · 1668 Da · 112 atoms

Sixteen residues sharing guanylin's crossed disulfides and cysteine spacing exactly. The two are close relatives, and both are drawn here.

Reference entry · not stocked