Proteins and peptides are susceptible to a variety of chemical modifications that can affect their structure and biological functions. Among these modifications, the isomerization of aspartic acid and deamidation of asparagine occur in proteins and peptides during aging. The reaction proceeds spontaneously under physiological conditions through a five-membered succinimide ring intermediate form...

Celiac disease (CD) is an intestinal disorder with multifactorial etiology. HLA and non-HLA genes together with gluten and possibly additional environmental factors are involved in disease development. Evidence suggests that CD4(+) T cells are central in controlling an immune response to gluten that causes the immunopathology, but the actual mechanisms responsible for the tissue damage are as y...

Cycle inhibiting factors (Cifs) are virulence proteins secreted by the type III secretion system of some Gram-negative pathogenic bacteria including Burkholderia pseudomallei. Cif is known to function to deamidate Nedd8, leading to inhibition of Cullin E3 ubiquitin ligases (CRL) and consequently induction of cell cycle arrest. Here we show that Cif can function as a potent activator of MAPK/ERK...

PURPOSE To determine age-related changes in the composition of the urea-soluble (US) protein fraction from lenses of senescence-accelerated OXYS (cataract model) and Wistar (control) rats and to establish posttranslational modifications (PTMs) occurring under enhanced oxidative stress in OXYS lenses. METHODS The identity and the relative abundance of crystallins in the US fractions were deter...

PURPOSE To elucidate the effect of deamidation on the structural and functional properties of human alphaB-crystallin. METHODS Site-directed mutagenesis was used to generate three deamidated mutants of alphaB-crystallin: N78D, N146D, and N78D/N146D. The mutations were confirmed by DNA sequencing and matrix-assisted desorption ionization-time of flight (MALDI-TOF) mass spectrometry. Recombinan...

There is a growing desire in the biological and clinical sciences to integrate and correlate multiple classes of biomolecules to unravel biology, define pathways, improve treatment, understand disease, and aid biomarker discovery. N-linked glycosylation is one of the most important and robust post-translational modifications on proteins and regulates critical cell functions such as signaling, a...

A plant transient expression system, with eukaryotic post-translational modification machinery, offers superior efficiency, scalability, safety, and lower cost over other expression systems. However, due to aberrant N-glycosylation, this expression system may not be a suitable expression platform for proteins not carrying N-linked glycans in the native hosts. Therefore, it is crucial to develop...

Glutamine--a popular nutritional supplement, non-toxic amino acid, and an essential interorgan and intercellular ammonia transporter--can destroy the neurons' mitochondria. When glutamine enters (like a Trojan horse) into the mitochondria, in the presence of glutaminase, it reacts with water and yields glutamate and excess ammonia which opens gates in the membrane of the mitochondria and thereb...