Konjugering af Alexa Fluor 488 til Insulin

Simon Hockenhull

Studenteropgave: Semesterprojekt

Abstrakt

Insulin is an important hormone used by the cells in the body for regulating the uptake of glucose. The insulin molecule consists of one A and one B chain. The chains contain 21 and 30 amino acids, respectively. Two sulphide bridges between the cysteine acids link the two chains together so that the protein can function. By staining the insulin with a fluorescent stain called Alexa Fluor 488, protein residues on a surface can be microscoped with a confocal microscope. In this project the sulphur bridges on stained and unstained insulin are reduced, forming unbound polypeptide chains and it is attempted to separate the chains in fractions by using the size chromatography, native and SDS PAGE, ion exchange chromatography and HPLC methods. The detector is a UV-Vis spectrophotometer. The proteins are measured in the ultraviolet range of 280 nm, and the stain is measured in the visual range of 490 nm. Size chromatography using PD10 column showed interaction with the column, and the insulin was retained. Native PAGE of the A and B chain did not show the expected separating bands. The SDS PAGE method proved more applicable but not for the purpose of this project. Ion exchange chromatography revealed fraction of the B chain in the first sample with an ABSmax at 276 nm and subsequently fraction of the A chain with an ABSmax at 271 nm. HPLC measurements confirmed these results and chromatograms showed that retention time for the colour peaks rose to the same level as for the A chain. The retention time for the A and B chain also rose after reaction with Alexa Fluor 488. Laboratory results showed that the B chain insulin may have been stained whereas this was apparently not the case for the A chain insulin.

UddannelserKemi, (Bachelor/kandidatuddannelse) Bachelor el. kandidat
SprogDansk
Udgivelsesdato20 jun. 2007
VejledereSøren Hvidt

Emneord

  • Insulin, A and B chain, HPLC, Staining, Alexa Fluor 488, Chromatography, isoelectric point, PAGE.