02685nas a2200229 4500008004100000022001400041245016600055210006900221260000800290300001600298490000600314520183500320100001802155700002402173700002002197700002302217700002002240700002002260700002002280700002502300856013002325 2022 eng d a2470-134300aInvestigation of the captopril-insulin interaction by mass spectrometry and computational approaches reveals that captopril induces structural changes in insulin0 aInvestigation of the captoprilinsulin interaction by mass spectr cJUL a23115-231260 v73 a

ABSTRACT: Post-translational modifications remarkably regulate proteins' biological function. Small molecules such as reactive thiols, metabolites, and drugs may covalently modify the proteins and cause structural changes. This study reports the covalent modification and noncovalent interaction of insulin and captopril, an FDA-approved antihypertensive drug, through mass spectrometric and computation-based approaches. Mass spectrometric analysis shows that captopril modifies intact insulin, reduces it into its ``A'' and ``B'' chains, and covalently modifies them by forming adducts. Since captopril has a reactive thiol group, it might reduce the insulin dimer or modify it by reacting with cysteine residues. This was proven with dithiothreitol treatment, which reduced the abundance of captopril adducts of insulin A and B chains and intact Insulin. Liquid chromatography tandem mass spectrometric analysis identified the modification of a total of four cysteine residues, two in each of the A and B chains of insulin. These modifications were identified to be Cys6 and Cys7 of the A chain and Cys7 and Cys19 of the B chain. Mass spectrometric analysis indicated that captopril may simultaneously modify the cysteine residues of intact insulin or its subunits A and B chains. Biophysical studies involving light scattering and thioflavin T assay suggested that the binding of captopril to the protein leads to the formation of aggregates. Docking and molecular dynamics studies provided insights into the noncovalent interactions and associated structural changes in insulin. This work is a maiden attempt to understand the detailed molecular interactions between captopril and insulin. These findings suggest that further investigations are required to understand the long-term effect of drugs like captopril.

1 aGhosh, Amrita1 aPawar, Aiswarya, B.1 aChirmade, Tejas1 aJathar, Swaraj, M.1 aBhambure, Rahul1 aSengupta, Durba1 aGiri, Ashok, P.1 aKulkarni, Mahesh, J. uhttps://library.ncl.res.in/content/investigation-captopril-insulin-interaction-mass-spectrometry-and-computational-approaches02486nas a2200277 4500008004100000022001400041245017700055210006900232260000900301300001400310490000700324520149400331653001201825653001301837653001801850653002201868653003301890653002501923100001901948700002001967700002301987700001502010700002602025700002502051856013202076 2024 eng d a0739-110200aDe novo structure prediction of meteorin and meteorin-like protein for identification of domains, functional receptor binding regions, and their high-risk missense variants0 aDe novo structure prediction of meteorin and meteorinlike protei cJUN  a4522-45360 v423 a

Meteorin (Metrn) and Meteorin-like (Metrnl) are homologous secreted proteins involved in neural development and metabolic regulation. In this study, we have performed de novo structure prediction and analysis of both Metrn and Metrnl using Alphafold2 (AF2) and RoseTTAfold (RF). Based on the domain and structural homology analysis of the predicted structures, we have identified that these proteins are composed of two functional domains, a CUB domain and an NTR domain, connected by a hinge/loop region. We have identified the receptor binding regions of Metrn and Metrnl using the machine-learning tools ScanNet and Masif. These were further validated by docking Metrnl with its reported KIT receptor, thus establishing the role of each domain in the receptor interaction. Also, we have studied the effect of non-synonymous SNPs on the structure and function of these proteins using an array of bioinformatics tools and selected 16 missense variants in Metrn and 10 in Metrnl that can affect the protein stability. This is the first study to comprehensively characterize the functional domains of Metrn and Metrnl at their structural level and identify the functional domains, and protein binding regions. This study also highlights the interaction mechanism of the KIT receptor and Metrnl. The predicted deleterious SNPs will allow further understanding of the role of these variants in modulating the plasma levels of these proteins in disease conditions such as diabetes.

10adomains10aMeteorin10ameteorin-like10amissense variants10aprotein-protein interactions10astructure prediction1 aShankar, Shiva1 aBanarjee, Reema1 aJathar, Swaraj, M.1 aRajesh, S.1 aRamasamy, Sureshkumar1 aKulkarni, Mahesh, J. uhttps://library.ncl.res.in/content/de-novo-structure-prediction-meteorin-and-meteorin-protein-identification-domains-functional02205nas a2200241 4500008004100000022001400041245009500055210006900150260000800219300001200227490000700239520141000246653002001656653002301676653001201699653002201711100002301733700002301756700002301779700001501802700002501817856012101842 2025 eng d a1572-388700aCharacterization of S-homocysteinylation of Human Insulin and Its Implications in Diabetes0 aCharacterization of Shomocysteinylation of Human Insulin and Its cOCT a598-6100 v443 a

Homocysteine thiolactone is a reactive thiol known for its interaction with various proteins. Nevertheless, there exists a paucity of information concerning the interaction between homocysteine thiolactone and human insulin, particularly regarding the mechanism by which homocysteine facilitates the reduction of disulfide bonds within insulin. In the present study, we have elucidated the binding sites of homocysteine to the cysteine residues (A6-B7 and A20-B19) that are implicated in the formation of intermolecular disulfide bonds in insulin through an in vitro reaction analyzed via LC-ESI MS/MS. This results in a reduction of disulfide bonds linking the A and B chains, which was corroborated by MALDI-TOF-MS and ESI-MS analysis. The secondary structure of insulin is affected by this modification, as evidenced by circular dichroism spectroscopy. In-silico studies also show that homocysteine affects the insulin structure. A glucose uptake assay conducted in Chinese hamster ovary (CHO) cells that stably express the insulin receptor revealed that HC-modified insulin is less effective in inducing glucose uptake compared to native insulin, suggesting that HC-induced structural modifications in insulin influence functional activity. This study provides insight into the HC-induced structural and functional changes in insulin and discusses the consequent implications for diabetes.

10aDisulfide bonds10aHomocysteinylation10ainsulin10aMass spectrometry1 aSheikh, Amreen, B.1 aJathar, Swaraj, M.1 aTammara, Vaishnavi1 aDas, Atanu1 aKulkarni, Mahesh, J. uhttps://library.ncl.res.in/content/characterization-s-homocysteinylation-human-insulin-and-its-implications-diabetes