Search

Organic synthesis often requires multiple steps where a functional group (FG) is concealed from reaction by a protecting group (PG). Common PGs include N-carbobenzyloxy (Cbz or Z) of amines and tert-butyloxycarbonyl (OtBu) of acids. An essential step is the removal of the PG, but this often requires excess reagents, extensive time and can have low % yield. An overarching goal of biocatalysis is to use "green" or "enzymatic" methods to catalyse chemical transformations. One under-utilised approach is the use of "deprotectase" biocatalysts to selectively remove PGs from various organic substrates. The advantage of this methodology is the exquisite selectivity of the biocatalyst to only act on its target, leaving other FGs and PGs untouched. A number of deprotectase biocatalysts have been reported but they are not commonly used in mainstream synthetic routes. This study describes the construction of a cascade to deprotect doubly-protected amino acids. The well known Bacillus BS2 esterase was used to remove the OtBu PG from various amino acid substrates. The more obscure Sphingomonas Cbz-ase (amidohydrolase) was screened with a range of N-Cbz-modified amino acid substrates. We then combined both the BS2 and Cbz-ase together for a 1 pot, 2 step deprotection of the model substrate CBz- L -Phe OtBu to produce the free L -Phe. We also provide some insight into the residues involved in substrate recognition and catalysis using docked ligands in the crystal structure of BS2. Similarly, a structural model of the Cbz-ase identifies a potential di-metal binding site and reveals conserved active site residues. This new biocatalytic cascade should be further explored for its application in chemical synthesis. [ABSTRACT FROM AUTHOR]

Background: Considering the inter-relationship between Diabetes Mellitus (DM) and oral tissues, assessment of oral health status in relation to glycemic control might be informative about the disease condition, which might be pivotal to appropriate management and ultimately improve life satisfaction. This study therefore aimed to assess the pattern of self-reported diabetes related oral conditions and oral health-related quality of life (OHRQoL) among patients with DM at the University College Hospital (UCH), Ibadan, Nigeria. Materials and methods: A cross- sectional study using an interviewer administered questionnaire was conducted among in- and out- patients being managed for DM by the Endocrinology unit of the hospital. Data collected included bio-data, medical history, self-reported oral conditions and dental service utilisation. The impact of oral health related quality of life was measured using OHIP-14. Oral examination was done to assess oral mucosal lesions and their oral hygiene status. Data was analysed using SPSS 21. Results: Eighty-four patients with diabetes consisting 23 (27%) in-patients and 61 (63%) out-patients were enrolled. Males were 26(31%) and females 58(69%); their ages ranged from 22 to 88 years with a mean of 60.9 ± 12.8 years. Most (67%) of the participants had one or more self-reported oral complaints, dryness (20.4%) being the most common and bad breath (4.6%) as the least reported. Poor glycemic level was found to be higher among the in-patients (82%) with random blood glucose > 200 mg/dL during admission, compared to the out-patient participants (51%) who had fasting plasma glucose > 110 mg/dL. Their oral hygiene status was assessed using simplified oral hygiene index and documented as fair (65%), poor (25%) and good (10%). About two-thirds (61%) had ever visited a dentist, majorly due to toothache. Only the pain (21.9%) and physical disability (26.3%) components of OHIP-14 were mainly found to affect the participants' OHRQOL. Conclusions: This study found high rate of self- reported DM related oral conditions notably oral dryness, and periodontal diseases particularly as teeth mobility and spontaneous exfoliation. Nonetheless, most of the study participants had fair OHRQoL while its physical pain, functional limitation and psychological disability components were most reported. [ABSTRACT FROM AUTHOR]