Glycerol 3-Phosphate Dehydrogenase Catalyzed Hydride Transfer: Enzyme Activation by Cofactor Pieces.

Glycerol 3-phosphate dehydrogenase catalyzes reversible hydride transfer from glycerol 3-phosphate (G3P) to NAD to form dihydroxyacetone phosphate; from the truncated substrate ethylene glycol to NAD in a reaction activated by the phosphite dianion substrate fragment; and from G3P to the truncated nicotinamide riboside cofactor in a reaction activated by adenosine 5'-diphosphate, adenosine 5'-monophosphate, and ribose 5-phosphate cofactor fragments. The sum of the stabilization of the transition state for GPDH-catalyzed hydride transfer reactions of the whole substrates by the phosphodianion fragment of G3P and the ADP fragment of NAD is 25 kcal/mol. Fourteen kcal/mol of this transition state stabilization is recovered as phosphite dianion and AMP activation of the reactions of the substrate and cofactor fragments.

Glycerol 3-Phosphate Dehydrogenase: Role of the Protein Conformational Change in Activation of a Readily Reversible Enzyme-Catalyzed Hydride Transfer Reaction.

Kinetic parameters are reported for glycerol 3-phosphate dehydrogenase (GPDH)-catalyzed hydride transfer from the whole substrate glycerol 3-phosphate (G3P) or truncated substrate ethylene glycol (EtG) to NAD, and for activation of the hydride transfer reaction of EtG by phosphite dianion. These kinetic parameters were combined with parameters for enzyme-catalyzed hydride transfer in the microscopic reverse direction to give the reaction equilibrium constants . Hydride transfer from G3P is favored in comparison to EtG because the carbonyl product of the former reaction is stabilized by hyperconjugative electron donation from the -CHR keto substituent.

Triosephosphate Isomerase: The Crippling Effect of the P168A/I172A Substitution at the Heart of an Enzyme Active Site.

The P168 and I172 side chains sit at the heart of the active site of triosephosphate isomerase (TIM) and play important roles in the catalysis of the isomerization reaction. The phosphodianion of substrate glyceraldehyde 3-phosphate (GAP) drives a conformational change at the TIM that creates a steric interaction with the P168 side chain that is relieved by the movement of P168 that carries the basic E167 side chain into a clamp that consists of the hydrophobic I172 and L232 side chains. The P168A/I172A substitution at TIM from (TIM) causes a large 120,000-fold decrease in for isomerization of GAP that eliminates most of the difference in the reactivity of TIM compared to the small amine base quinuclidinone for deprotonation of catalyst-bound GAP.

Effect of Whole-Body Vibration Exercise on Hamstrings-to-Quadriceps Ratio, Walking Performance, and Postural Control in Children With Hemiparetic Cerebral Palsy: A Randomized Controlled Trial.

Objective: The purpose of this study was to investigate the effect of whole-body vibration (WBV) exercises combined with traditional physiotherapy on the hamstrings-to-quadriceps (H:Q) ratio, walking ability, and control of posture in children with hemiparetic cerebral palsy (CP).

Methods: A total of 34 children with spastic hemiparetic CP (boys and girls) participated in this 2-arm, parallel, randomized controlled trial. The inclusion criteria were spasticity ranging from 1 to 1+, gross level skills (I and II), at least 1 meter tall, standing alone, and walking forward and backward.

The Role of Asn11 in Catalysis by Triosephosphate Isomerase.

Four catalytic amino acids at triosephosphate isomerase (TIM) are highly conserved: N11, K13, H95, and E167. Asparagine 11 is the last of these to be characterized in mutagenesis studies. The ND2 side chain atom of N11 is hydrogen bonded to the O-1 hydroxyl of enzyme-bound dihydroxyacetone phosphate (DHAP), and it sits in an extended chain of hydrogen-bonded side chains that includes T75' from the second subunit.

Blake's pouch cyst and Werdnig-Hoffmann disease: Report of a new association and review of the literature.

Background: We report a case of a neonate with proximal spinal muscular atrophy (SMA) type 1 (also known as Werdnig-Hoffmann disease or severe infantile acute SMA) associated with a Blake's pouch cyst; a malformation that is currently classified within the spectrum of Dandy-Walker complex. The association of the two conditions has not been previously reported in the English literature. A comprehensive review of the pertinent literature is presented.

Computed tomographic evaluation of C5 root exit foramen in patients with cervical spondylotic myelopathy.

Background: Narrowing of the intervertebral foramen for C5 root and a larger superior articular process in myelopathic patients with postlaminoplasty motor dominant C5 radiculopathy has been reported. We investigated whether the C4-5 foraminal dimensions and surface area in patients with cervical spondylotic myelopathy are universally smaller than the intervertebral foramina at other cervical levels.

Methods: The study population consisted of 44 consecutive patients (sex: 24 males and 20 females), averaging 55.

Computed tomographic evaluation of the distance between the medial border of longus colli muscle and foramen transversarium in ventral approaches to the subaxial cervical spine.

Aim: Iatrogenic vertebral artery (VA) injury during ventral approaches to the subaxial cervical spine ranges from 0.22% to 2.77%.