RESUMO
Polyethylene terephthalate (PET) is one of the highly produced synthetic polymers worldwide and had acquired attention due to its impact resistance, high clarity, and light weight. PET has become the first choice in making disposable bottles, leading to massive scales of production resulting in very high utilization across various facets of our daily life. Unfortunately, PET accumulates as waste and is highly resistant to biodegradation, thus presenting a serious threat to the ecosystem. Degradation of PET by enzymatic hydrolysis is a promising strategy to depolymerize the PET into its monomers. In recent studies, a plastic-degrading enzyme known as PETase (IsPETase) from the Ideonella sakaiensis has been identified to hydrolyze PET. The wild-type enzyme from Ideonella sp., has been engineered to improve the catalytic activity. While the IsPETase and its variants have been the subject of extensive structural and biochemical studies, the corresponding computational studies to support the improved activity of the mutant enzyme is not fully understood. In this work, we employed all-atom classical molecular dynamics simulations of the wild-type and double mutant IsPETase enzymes to investigate the underlying reason for the improved catalytic activity in the double mutant by means of structure-dynamics-function relationship. Our results show that the engineered mutations reshape the active site structure, volume, and dynamics of the protein loops which is crucial for substrate binding. We also demonstrate that addition of aromatic and hydrogen bond-forming residues near catalytic site improves binding affinity. This work will enable the rational design of mutants for enhanced PET degrading activity.Communicated by Ramaswamy H. Sarma.
RESUMO
This study aims to report two distinct cases of adenomatoid odontogenic tumor (AOT) with contrasting presentations. The first case involved a 12-year-old female patient with the presence of AOT in the posterior mandible extending into the mandibular ramus up till the coronoid process which is a rare reported site for AOT and the second case is of a 19-year-old male patient with the tumor in the anterior maxilla with an impacted central incisor. Both cases were successfully managed via surgical enucleation and are under regular follow-ups without any complication. The contrasting nature of the two clinical presentations with the same pathologic entity is reported here. Though AOT has been rarely reported extending into the mandibular ramus, a maxillofacial surgeon should be more circumspect of this pathology while dealing with benign swellings of the mandibular posterior region.
RESUMO
INTRODUCTION: Peripheral ossifying fibromas (POFs) and pyogenic granulomas (PGs) are non-neoplastic reactive lesions of gingiva that usually affect young females and are usually located in the anterior maxilla. It is possible to misdiagnose POF as PG, peripheral giant cell granuloma, or odontogenic tumors. Histopathologic examination is recommended and is essential for an accurate diagnosis of such lesions, and differential diagnosis is also important because POFs have a tendency to recur. CASE PRESENTATION: A clinical case of gingival swelling in the mandibular left second premolar and first molar region on the lingual side, which was diagnosed as a POF on histopathologic examination, is reported. Recurrence of the lesion was seen within 1 week of its excision. The recurrent overgrowth was again excised, thoroughly curetted, and histopathologically confirmed as a PG. No signs of recurrence were seen at the 6-month follow-up. CONCLUSION: This case shows the importance of complete excision of the lesion to the entire depth with curettage of the adjacent tissues for prevention of recurrence.
