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"Payton was a beautiful baby girl — but she would not sit up. Four months passed, and similar milestones seemed to slip away. She wouldn\'t roll over. She wouldn\'t play with her toys. She still wouldn\'t sit up. Payton\'s symptoms progressively worsened. Loud noises inexplicably startled her. An inability to coordinate muscle movement between her mouth and tongue caused her to choke on food and produce excessive saliva." Because neither of Peyton\'s parents were Jewish, Her doctors did not suspect Tay-Sachs disease until she was 10 months old, when her ophthalmologist noticed the cherry red spots in her eyes. Payton died in 2006 at the age of 3½.
***Deficiency in any one of these proteins leads to storage of the ganglioside. Mutation from the gene cause incorrect folding.
GM2 is presented to Hex A by the GM2 activator
protein (GM2AP). Hex A removes the terminal
b-linked GalNAc from the GM2 ganglioside to
produce the GM3 ganglioside
In both active sites of beta and alpha subunits, a glutamate residue acts as a general
acid-base that assists in cleaving the terminal b-linked GalNAc or GlcNAc residues from
substrates; whereas an adjacent aspartateresidue stabilizes the positively charged
oxazolinium intermediate that develops during the substrate-assisted catalytic mechanism
carried outbyhuman Hex
the severity of the GM2 gangliosidosisphenotype, red for acute to subacute, green for chronic and blue for asymptomatic (mutations that lower Hex A activity, but not below the critical threshold needed to prevent storage). The majority of residues involved in acute and chronic TSD are located throughout domain II of the a-subunit, distributed amongst the b-strands and helices comprising the TIM barrel. Notably, only a few mutations are found among residues of the active site.