Acid stabilization of insulin.


The effect of pH on the conformational stability of insulin was studied. Surprisingly, the Gibbs free energy of unfolding increased approximately 30% by acidification. pH titration of insulin's conformational stability is described by a transition involving a single proton with an apparent pK(a) of 7.0. The acid stabilization of insulin's conformation was attributed to the protonation of histidine at position 5 on the B-chain (HB5) as determined by 1H-NMR of the histidines, selective amino acid alteration, and enthalpies of ionization. Further acidification (at least to pH 2) does not decrease the free energy of unfolding. A conformational change in the tertiary structure, as indicated by the near-UV circular dichroism spectrum, accompanies this change in stability. We propose that this acid stabilization of insulin is physiologically important in maintaining insulin stability in the acid environment of the secretory/storage granules of the beta-cell of the pancreatic islets of Langerhans. Study holds ProTherm entries: 4550, 4551, 4552, 4553, 4554 Extra Details: additive : EDTA(1 mM), acidification; transition; protonation; conformational change;,tertiary structure

Submission Details

ID: cHi7KfrA3

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:26 p.m.

Version: 1

Publication Details
Bryant C;Spencer DB;Miller A;Bakaysa DL;McCune KS;Maple SR;Pekar AH;Brems DN,Biochemistry (1993) Acid stabilization of insulin. PMID:8394123
Additional Information

Structure view and single mutant data analysis

Study data

No weblogo for data of varying length.
Colors: D E R H K S T N Q A V I L M F Y W C G P

Data Distribution

Studies with similar sequences (approximate matches)

Correlation with other assays (exact sequence matches)

Relevant UniProtKB Entries

Percent Identity Matching Chains Protein Accession Entry Name
1200.0 A,B,C,D,E,F,G,H,I,J,K,L Insulin P67973 INS_BALPH
1200.0 A,B,C,D,E,F,G,H,I,J,K,L Insulin P01321 INS_CANLF
1200.0 A,B,C,D,E,F,G,H,I,J,K,L Insulin P30407 INS_CHLAE
1200.0 A,B,C,D,E,F,G,H,I,J,K,L Insulin Q6YK33 INS_GORGO
1200.0 A,B,C,D,E,F,G,H,I,J,K,L Insulin P01308 INS_HUMAN
1180.2 A,B,C,D,E,F,G,H,I,J,K,L Insulin Q91XI3 INS_ICTTR
1200.0 A,B,C,D,E,F,G,H,I,J,K,L Insulin P30406 INS_MACFA
1200.0 A,B,C,D,E,F,G,H,I,J,K,L Insulin P30410 INS_PANTR
1200.0 A,B,C,D,E,F,G,H,I,J,K,L Insulin P67974 INS_PHYMC
1200.0 A,B,C,D,E,F,G,H,I,J,K,L Insulin P01315 INS_PIG
1200.0 A,B,C,D,E,F,G,H,I,J,K,L Insulin Q8HXV2 INS_PONPY
1180.2 A,B,C,D,E,F,G,H,I,J,K,L Insulin P01311 INS_RABIT
571.2 A,C,E,G,I,K Insulin P01325 INS1_MOUSE
571.2 A,C,E,G,I,K Insulin P01322 INS1_RAT
1149.6000000000001 A,B,C,D,E,F,G,H,I,J,K,L Insulin P01326 INS2_MOUSE
1149.6000000000001 A,B,C,D,E,F,G,H,I,J,K,L Insulin P01323 INS2_RAT
1131.0 A,B,C,D,E,F,G,H,I,J,K,L Insulin P01324 INS_ACOCA
1151.4000000000003 A,B,C,D,E,F,G,H,I,J,K,L Insulin P01313 INS_CRILO
1171.2 A,B,C,D,E,F,G,H,I,J,K,L Insulin P01310 INS_HORSE
1171.2 A,B,C,D,E,F,G,H,I,J,K,L Insulin Q62587 INS_PSAOB
1143.0 A,B,C,D,E,F,G,H,I,J,K,L Insulin P01316 INS_ELEMA
1143.0 A,B,C,D,E,F,G,H,I,J,K,L Insulin P01317 INS_BOVIN
1122.6 A,B,C,D,E,F,G,H,I,J,K,L Insulin P01320 INS_CAMDR
543.0 A,C,E,G,I,K Insulin P01327 INS_CHICH
1143.0 A,B,C,D,E,F,G,H,I,J,K,L Insulin P01314 INS_BALBO
1143.0 A,B,C,D,E,F,G,H,I,J,K,L Insulin P18109 INS_DIDVI
600.0 B,D,F,H,J,L Insulin F8WCM5 INSR2_HUMAN
600.0 B,D,F,H,J,L Insulin P01319 INS_CAPHI
600.0 B,D,F,H,J,L Insulin P06306 INS_FELCA
600.0 B,D,F,H,J,L Insulin P01318 INS_SHEEP
559.8 B,D,F,H,J,L Insulin P67972 INS_AOTTR
559.8 B,D,F,H,J,L Insulin P67971 INS_SAISC
578.4 B,D,F,H,J,L Insulin P01333 INS_ANAPL
578.4 B,D,F,H,J,L Insulin P68245 INS_ANSAN
578.4 B,D,F,H,J,L Insulin P68243 INS_CAIMO
578.4 B,D,F,H,J,L Insulin P51463 INS_SELRF
577.8 B,D,F,H,J,L Insulin P67970 INS_CHICK
577.8 B,D,F,H,J,L Insulin P67968 INS_MELGA
577.8 B,D,F,H,J,L Insulin P67969 INS_STRCA
577.8 B,D,F,H,J,L Insulin P69047 INS_TRADO
577.8 B,D,F,H,J,L Insulin P69048 INS_TRASC
557.4 B,D,F,H,J,L Insulin P12706 INS1_XENLA
600.0 B,D,F,H,J,L Insulin P81423 INS_ACIGU
579.6 B,D,F,H,J,L Insulin P21563 INS_RODSP
577.2 B,D,F,H,J,L Insulin C0HJI8 INS2_HUSDA
555.6 B,D,F,H,J,L Insulin P12707 INS2_XENLA
558.6 B,D,F,H,J,L Insulin P83770 INSL_VIGUN
555.6 B,D,F,H,J,L Insulin P01340 INS_KATPE
553.8 B,D,F,H,J,L Insulin P04667 INS_ONCKE
553.8 B,D,F,H,J,L Insulin P09477 INS_PLAFE
553.8 B,D,F,H,J,L Insulin Q9W7R2 INS_VERMO
553.8 B,D,F,H,J,L Insulin P09476 INS_ATRSP
553.8 B,D,F,H,J,L Insulin C0HJI3 INS2_KATPE
555.6 B,D,F,H,J,L Insulin C0HJI7 INS1_HUSDA
550.2 B,D,F,H,J,L Insulin P68988 INS_LAMFL
550.2 B,D,F,H,J,L Insulin P68987 INS_PETMA
547.8 B,D,F,H,J,L Insulin P01338 INS2_BATSP