Editing C-peptide (section)

{{Short description|Insulin production indicator protein}}
{{cs1 config|name-list-style=vanc}}
{{distinguish|C-reactive protein|Protein C}}
{{Use British English|date=October 2019}}
{{Use mdy dates|date=March 2024}}
{{chembox
| Verifiedfields = changed
| Watchedfields = changed
| verifiedrevid = 448959307
| ImageFile=C-Peptide.svg
| ImageClass = skin-invert-image
| ImageSize=275px
| IUPACName=
| OtherNames=
| Reference=<ref>[https://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=16132309 C-Peptide - Compound Summary] {{Webarchive|url=https://web.archive.org/web/20121017163555/http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=16132309 |date=October 17, 2012 }}, [[PubChem]].</ref>
|Section1={{Chembox Identifiers
| CASNo_Ref = {{cascite|correct|CAS}}
| CASNo=59112-80-0
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = O2J76Y002M
| MeSHName=C-Peptide
| PubChem = 16132309
| ChemSpiderID_Ref = {{chemspidercite|changed|chemspider}}
| ChemSpiderID = 17288968
| SMILES = CC(C)CC(C(=O)NC(C)C(=O)NC(CC(C)C)C(=O)NC(CCC(=O)O)C(=O)NCC(=O)NCC(=O)NCC(=O)NC(CCC(=O)N)C(=O)O)NC(=O)CNC(=O)C(CCC(=O)N)NC(=O)C(CC(C)C)NC(=O)CNC(=O)CNC(=O)C(C)NC(=O)CNC(=O)C1CCCN1C(=O)CNC(=O)CNC(=O)CNC(=O)C(CC(C)C)NC(=O)C(CCC(=O)O)NC(=O)CNC(=O)C(CCC(=O)N)NC(=O)CNC(=O)C(C(C)C)NC(=O)C(CCC(=O)N)NC(=O)CNC(=O)C(CC(=O)O)NC(=O)C(CCC(=O)O)NC(=O)CNC(=O)C(CCC(=O)O)N
| InChI = 1/C112H179N35O46/c1-51(2)32-66(144-104(184)63(21-29-92(170)171)137-85(161)46-127-99(179)59(16-23-72(114)148)134-87(163)49-131-111(191)95(55(9)10)146-106(186)62(18-25-74(116)150)135-86(162)47-129-103(183)70(36-94(174)175)145-105(185)64(22-30-93(172)173)136-84(160)45-124-98(178)58(113)15-27-90(166)167)102(182)126-41-80(156)119-38-77(153)122-50-89(165)147-31-13-14-71(147)110(190)130-44-81(157)132-56(11)96(176)123-39-78(154)121-43-83(159)140-68(34-53(5)6)108(188)141-60(17-24-73(115)149)100(180)128-48-88(164)139-67(33-52(3)4)107(187)133-57(12)97(177)143-69(35-54(7)8)109(189)142-61(20-28-91(168)169)101(181)125-40-79(155)118-37-76(152)120-42-82(158)138-65(112(192)193)19-26-75(117)151/h51-71,95H,13-50,113H2,1-12H3,(H2,114,148)(H2,115,149)(H2,116,150)(H2,117,151)(H,118,155)(H,119,156)(H,120,152)(H,121,154)(H,122,153)(H,123,176)(H,124,178)(H,125,181)(H,126,182)(H,127,179)(H,128,180)(H,129,183)(H,130,190)(H,131,191)(H,132,157)(H,133,187)(H,134,163)(H,135,162)(H,136,160)(H,137,161)(H,138,158)(H,139,164)(H,140,159)(H,141,188)(H,142,189)(H,143,177)(H,144,184)(H,145,185)(H,146,186)(H,166,167)(H,168,169)(H,170,171)(H,172,173)(H,174,175)(H,192,193)/t56-,57-,58-,59-,60-,61-,62-,63-,64-,65-,66-,67-,68-,69-,70-,71-,95-/m0/s1
| InChIKey = XTUNIGNWBZZIPT-NTMYLOQBBL
| StdInChI_Ref = {{stdinchicite|changed|chemspider}}
| StdInChI = 1S/C112H179N35O46/c1-51(2)32-66(144-104(184)63(21-29-92(170)171)137-85(161)46-127-99(179)59(16-23-72(114)148)134-87(163)49-131-111(191)95(55(9)10)146-106(186)62(18-25-74(116)150)135-86(162)47-129-103(183)70(36-94(174)175)145-105(185)64(22-30-93(172)173)136-84(160)45-124-98(178)58(113)15-27-90(166)167)102(182)126-41-80(156)119-38-77(153)122-50-89(165)147-31-13-14-71(147)110(190)130-44-81(157)132-56(11)96(176)123-39-78(154)121-43-83(159)140-68(34-53(5)6)108(188)141-60(17-24-73(115)149)100(180)128-48-88(164)139-67(33-52(3)4)107(187)133-57(12)97(177)143-69(35-54(7)8)109(189)142-61(20-28-91(168)169)101(181)125-40-79(155)118-37-76(152)120-42-82(158)138-65(112(192)193)19-26-75(117)151/h51-71,95H,13-50,113H2,1-12H3,(H2,114,148)(H2,115,149)(H2,116,150)(H2,117,151)(H,118,155)(H,119,156)(H,120,152)(H,121,154)(H,122,153)(H,123,176)(H,124,178)(H,125,181)(H,126,182)(H,127,179)(H,128,180)(H,129,183)(H,130,190)(H,131,191)(H,132,157)(H,133,187)(H,134,163)(H,135,162)(H,136,160)(H,137,161)(H,138,158)(H,139,164)(H,140,159)(H,141,188)(H,142,189)(H,143,177)(H,144,184)(H,145,185)(H,146,186)(H,166,167)(H,168,169)(H,170,171)(H,172,173)(H,174,175)(H,192,193)/t56-,57-,58-,59-,60-,61-,62-,63-,64-,65-,66-,67-,68-,69-,70-,71-,95-/m0/s1
| StdInChIKey_Ref = {{stdinchicite|changed|chemspider}}
| StdInChIKey = XTUNIGNWBZZIPT-NTMYLOQBSA-N
  }}
|Section2={{Chembox Properties
| Formula=C<sub>129</sub>H<sub>211</sub>N<sub>35</sub>O<sub>48</sub>
| MolarMass=3020.29 g/mol
| Appearance=
| Density=
| MeltingPt=
| BoilingPt=
| Solubility=
  }}
|Section3={{Chembox Hazards
| MainHazards=
| FlashPt=
| AutoignitionPt =
  }}
}}

The '''connecting peptide''', or '''C-peptide''', is a short 31-amino-acid polypeptide that connects [[insulin|insulin's]] A-chain to its B-chain in the [[proinsulin]] molecule. In the context of diabetes or hypoglycemia, a measurement of C-peptide blood serum levels can be used to [[Differential diagnosis|distinguish]] between different conditions with similar clinical features.

In the insulin synthesis pathway, first [[preproinsulin]] is translocated into the [[endoplasmic reticulum]] of [[beta cell]]s of the pancreas with an A-chain, a C-peptide, a B-chain, and a [[signal peptide|signal sequence]]. The signal sequence is cleaved from the [[N-terminus]] of the peptide by a [[signal peptidase]], leaving [[proinsulin]]. After proinsulin is packaged into vesicles in the [[Golgi apparatus]] (beta-granules), the C-peptide is removed, leaving the A-chain and B-chain bound together by disulfide bonds, that constitute the insulin molecule.