The base catalyzed elimination of the suffhydryl protecting group affords dehydroalanine and the subsequent addition of piperidine yields the C-terminally modified peptide . This side reaction is minimized (but not avoided!) when trityl is used for the protection of the C-terminal Cys.
This reaction occurs when Trp is used unprotected. The addition of Pmc (or Pbf) to the indole ring will occur and the amount of by-product is related to the distance between the Trp and the Arg residues .
This line is what makes up a Protein.
The tRNA reads the mRNA.
Most enzymes are proteins, but RNA
molecules can be enzymes too.
The ribosome is not only complex, but it is also the most important part of the biological cell, along with the necessary information
needed to make proteins (encoded in DNA or RNA).
Initially, the membrane transport protein (also called a carrier)is in its closed configuration which does not allow substrates or othermolecules to enter or leave the cell.
Usually the color is developed mainly in the beads and partly in the supernatant; but for spectrometric quantitative determination of the amount of unreacted amino groups the color has to be transferred completely to the solution . The intensity of the color depends on the nature of the amino terminus to be detected; rather unspecific shades are obtained with N-terminal (side-chain protected!) Asp, Asn, Cys, Ser, and Thr. Brownish red beads result with N-terminal Pro. As the resin sample has to be heated, “hidden” NH2-groups may become more accessible and thus detectable. However, prolonged heating as well as overheating should be avoided as it may cause Lys(Boc) cleavage or Fmoc removal (by pyridine).
As electrons are transferred along the electron-transport chain, the energy released is used to pump protons (H+) from the mitochondrial matrix into the mitochondrial intermembrane space.
After the cleavage the sample is analyzed by HPLC as Fmoc protected and free amino sequences are usually well separated in a standard HPLC gradient.
AAC is a membrane protein that acts like a revolving door - transporting ADP into mitochondria (to be converted to ATP) and ATP out of mitochondria and into the cytoplasm (Wang and Tajkhorshid 2008).
This attachment of aphosphate group to the carrier molecule causes a conformational changein (or achange in the shape of ) the protein so that a channel opens between theinside and outside of the cell membrane.
Capping is realized through a short treatment of the peptide resin with a large excess of a highly reactive unhindered acid derivative and abase, usually acetic anhydride or benzoyl chloride and pyridine. At the end of the capping step the reagents are filtered off and the resin is carefully washed before proceeding to the next deprotection step.
CAUTION: DCC is an aggressive allergen. Inhalation and contact must be avoided; adequate protection must be worn when working with DCC and efficient ventilation is also required!
In a standard coupling procedure the HOBt ester is generated by the reaction between the protected amino acid and HOBt. The reaction is mediated by DCC or DIC.
Repeated incomplete deprotection of the αamino function as well as difficulties in obtaining a complete coupling reaction are some of the problems caused by the on resin aggregation of the peptide chain.
Ultimately, the string of amino acids folds upon itself, adopting the unique shape that is the signature of that particular protein. Source: