O-Sulfation

Overview O-Sulfation is a common post-translational modification of tyrosine residues in eukaryotes, but has not been observed in yeast and prokaryotes. Sulfation is limited to secretory and trans-membrane proteins that have passed the trans-Golgi network, where two membrane-bound tyrosylprotein sulfotransferase enzymes catalyze the transfer of sulfate from adenosine 3’-phosphate5’-phosphosulfate to the tyrosine phenol. pKa NC […]

Nitration

Overview Nitration is a post-translational modification of mostly tyrosine residues that is caused by one-electron oxidation. First, a tyrosine radical is formed by one-electron oxidation followed by a reaction with nitrogen dioxide resulting in 3-nitrotyrosine. pKa NC Loss Gain Deltamass H AA UV-Spec Pattern Acidic7.25 No H NO2 Av: 44.9976M: 44.9851 – Y Yes* – […]

Amidation

Amidation is one of the most common post-translational modification in which the C-terminal carboxyl group is replaced by an amide group​1–5​. Amidation plays an important role in peptidesand peptide hormones. More than half of all mammalian peptide hormones and more than 80 % of all insect hormones have amidated C-termini​1​. The mechanism of amidation is […]

A mass spectrometry imaging software: Quantinetix™

ImaBiotech, founded in 2009 by a team of experts, offers new molecular imaging (called MALDI imaging) services and products to life science industries. This new technology is capable of visualizing and quantifying biological compounds that play role in many pathologies like Cancer, Alzheimer or Parkinson diseases. It is also an interesting tool to follow new […]

Prediction of potential modification sites in proteins

Some sequence motifs in proteins tend to be modified. Thus, for example an N-terminal glutamine or glutamic acid residue can spontaneously lead to a cyclization. This reaction results in an N-terminal pyroglutamic acid with elimination of ammonia or water, respectively. Aspartyl and asparaginyl deamidation, isomerization, and racemization reactions can spontaneously occur, if the subsequent amino acid […]

Molecular mass and isoelectric point calculator for glycosylated proteins

Glycosylations should not be neglected for the correct calculation of the molecular mass, the isoelectric point and the mass-specific UV absorption coefficient. Therefore Prot pi provides a tool to draw glycans as a posttranslational modification of proteins. This short guide deals with how to add two complex-type N-Glycosylation G1 with a sialic acid (N-acetylneuraminic acid) […]

Isoelectric point calculation of native proteins

The isoelectric point (pI) of native (not denaturated) proteins is important in several separation techniques. The pI is defined as the pH value at which the positive and negative charges on the protein are balanced and the net charge is zero. To determine the pH at which the net charge is zero, the charge on […]

Bioinformatics (from Wikipedia)

This is the definition from Wikipedia: Bioinformatics is an interdisciplinary field that develops methods and software tools for understanding biological data. As an interdisciplinary field of science, bioinformatics combines computer science, statistics, mathematics, and engineering to study and process biological data. [ratings]