Calmodulin-SH, Wheat (Triticum aestivum)

The presence of Cysteine 26 in Wheat germ (Triticum aestivum) calmodulin (CaM) makes it unique vis-a-vis mammalian calmodulin. In contrast to mammalian CaMs, which lack cysteine, this preparation is ideal for applications requiring both calmodulin activation and residue specific tagging. The single SH moiety at Cys26 can be labeled using a variety of sulfhydryl (SH) reactive protein-modification reagents such as fluorescent maleimide derivatives. The presence of a single C-terminal tyrosine residue at the138 position (Tyr138) as against two tyrosines in mammalian calmodulin makes Tyr138 suitable as a mono-specific tag. Using Cys26 and Tyr138 allows wheat germ CaM to be independently derivatized at both N- and C-terminal regions within the molecule for structural, proteomic biomarker discovery and protein-protein interaction studies. Wheat germ CaM also has no tryptophan resulting in a distinctive absorbance spectrum when compared to mammalian CaM sequences. Calmodulin (CaM) is a ubiquitous, calcium-binding protein that binds and regulates a multitude of protein targets, many of which are involved in the Alzheimer's and the Parkinson's pathways1, 4. CaM has a molecular weight of about 17kDa, containing 148 amino acids, and pI of 3.9. CaM is characterized by two domains, connected by an alpha-helix chain. Each domain has the capacity to bind two calcium ions. Binding Ca2+ ions causes a conformational change in CaM, making it available for interaction with target proteins. Hence, CaM functions as an intracellular calcium ion bridge to mediate cellular reactions and responds appropriately to calcium ion concentration. In Alzheimer's disease (AD), irregular calcium homeostasis seems to trigger CaM and its binding proteins, to enhance plaque formation and neurofibrillary degeneration, which results in cell death1. The increased cytosolic levels of Ca2+ in AD neurons promotes CaM binding and regulation of available Ca2+/CaM-dependent CaM-binding proteins, associated with amyloid beta (Ab) formation. In addition, the increased level of Ca2+ triggers Calmodulin to activate calcium/CaM-dependent kinase II and precede neurofibrillary tangle formation2, 4. In Parkinson's disease (PD), Calmodulin has been found to interact, in a calcium dependent manner, with Alpha-Synuclein, which is associated with the progression of PD. CaM was identified as one of the synuclein-interacting proteins that regulate synuclein conformation3.

16, 750 Da