Using BpyAla to generate copper artificial metalloenzymes: a catalytic and structural study.

Artificial metalloenzymes (ArMs) have emerged as a promising avenue in the field of biocatalysis, offering new reactivity. However, their design remains challenging due to the limited understanding of their protein dynamics and how the introduced cofactors alter the protein scaffold structure. Here we present the structures and catalytic activity of novel copper ArMs capable of (R)- or (S)-stereoselective control, utilizing a steroid carrier protein (SCP) scaffold. To incorporate 2,2'-bipyridine (Bpy) into SCP, two distinct strategies were employed: either Bpy was introduced as an unnatural amino acid (2,2'-bipyridin-5-yl)alanine (BpyAla) using amber stop codon expression or via bioconjugation of bromomethyl-Bpy to cysteine residues. The resulting ArMs proved to be effective at catalysing an enantioselective Friedel-Crafts reaction with SCP_Q111BpyAla achieving the best selectivity with an enantioselectivity of 72% ee (S). Interestingly, despite using the same protein scaffold, different attachment strategies for Bpy at the same residue (Q111) led to a switch in the enantiopreference of the ArM. X-ray crystal structures of SCP_Q111CBpy and SCP_Q111BpyAla ArMs with bound Cu(ii) ions unveiled crucial differences in the orientation of the catalytic centre. Combining structural information, alanine scanning studies, and computational analysis shed light on the distinct active sites of the ArMs, clarifying that these active sites stabilise the nucleophilic substrate on different sides of the electrophile leading to the observed switch in enantioselectivity. This work underscores the importance of integrating structural studies with catalytic screening to unravel the intricacies of ArM behaviour and facilitate their development for targeted applications in biocatalysis.

Extra-abdominal desmoid tumors.

One hundred and ninety-four patients with extra-abdominal desmoid tumors, most of them in the extremities, have been treated at the Mayo Clinic. One hundred and thirty-two patients (68 per cent) experienced a recurrence at an average of 1.4 years after the first treatment. A greater tendency for recurrence was evident in female patients, in patients who were more than thirty years old, in certain anatomical locations (especially the foot and calf), and most importantly after treatment by intralesional or marginal excision. In view of the excellent prognosis for survival, we recommend wide local excision when anatomically feasible or marginal excision and postoperative radiation therapy when function of the extremity would be severely compromised if excision with wide margins were done. A recurrent lesion that does not appear to be growing should be followed until evidence of growth of the lesion precipitates a secondary wide excision.

Force and motion analysis of the normal, diseased, and prosthetic ankle joint.

A 2-dimensional motion and force study of the ankle joint during gait has been carried out on normal subjects and patients with ankle joint disease, before and 1 year following total ankle replacemetn. The methods employed involved the use of high-speed motion picture film, force plate and foot-switch data. The Achilles and anterior tibial tendon forces, the compressive and tangential (shear) forces across the ankle during stance phase of gait were determined, based on a quasi-static analysis. During stance phase of gait normal subjects used a mean of 24.4 degree of sagittal plane ankle motion. Patients with ankle joint disease showed reduced motion which returned to near normal values 1 year following total ankle replacement. Compressive force across the ankle joint rose to about 5 times body weight during the latter part of stance phase. Backward, or aft, shear forces or nearly full body weight were demonstrated during all but the last 20% of stance phase. Patients with ankle joint disease apparently altered their gait to markedly reduce these forces. Following total ankle replacement, shear forces returned toward more normal values, but compressive forces were not significantly changed.

Conversion of the arthrodesed hip to a total hip arthroplasty.

Total hip arthroplasty was done in thirty-three patients who had had previous surgical attempts at arthrodesis of the hip. The arthrodesis had failed in nineteen patients, and the other fourteen patients had fused hips with symptoms in the knee and lower back. Thirty-one of the patients had satisfactory functional ability after total hip arthroplasty after one to three and one-half years' follow-up. The two patients in whom the procedure failed had complicating infections.