Purification and characterization of novel isoforms of the polyphenol oxidase from Malus domestica fruit pulp.

Polyphenol oxidases (PPOs), belong to the group of oxidoreductases that are copper containing enzymes and are responsible for plant browning. PPOs are extensively distributed in plant kingdom and can oxidize wide range of aromatic compounds of industrial importance. The aim of this study was purification and characterization of PPO isoforms from the fruit pulp of Golden delicious apple. High performance liquid chromatography was used to purify the two novel isoforms of PPO and further their molecular weights (45 and 28 kDa) were determined using sodium dodecyl sulfate polyacrylamide gel electrophoresis. The purified isoforms have optimum pH (6.5), optimum temperature (40°C), the Vmax (4.45 µM/min) and Km (74.21 mM) with catechol substrate. The N-terminal microsequences of both PPO isoforms were determined using a pulse liquid protein sequencer and found to be AKITFHG (28 kDa) and APGGG (45 kDa). Polyphenol oxidases are efficiently used in the pharmaceutical, paper and pulp, textiles and food industries. Recently, the PPOs have been used for bioremediation and in the development of biosensors.

Antecedent infections, recent developments and future directions in Guillain-Barré syndrome.

The Guillain-Barré syndrome is an autoimmune polyradiculoneuropathy causing symmetrical weakness of limbs. After poliomyelitis, it is the second most common cause of paralysis, with an annual incidence of 0.84-1.91 per 100,000 individuals. The syndrome affects both men and women, showing a male preponderance. Campylobacter jejuni, epstein-barr virus, cytomegalovirus, mycoplasma pneumoniae and haemophilus influenzae are amongst the most common causative agents of Guillain-Barré syndrome. Several immunological and genetic factors have been recognised as the risk factors. Human leukocyte antigen, cluster of differentiation 1, and tumour necrosis factor-alpha alleles are among the frequently investigated loci in Guillain-Barré syndrome. Genome-wide association studies have found no significant association of Guillain-Barré syndrome with common variants. Many vaccines against Campylobacter jejuni infection have been proposed, but there are concerns about the efficacy and safety of these vaccines. So far, there is no approved vaccine against Campylobacter jejuni.