THE USE OF DEDICATED PEPTIDE LIBRARIES PERMITS THE DISCOVERY OF HIGH-AFFINITY BINDING PEPTIDES

The motif for peptide binding to monoclonal antibody mAb A16, which is known to be directed against glycoprotein D of Herpes simplex virus type 1, was determined using two dedicated peptide libraries. As a starting point for this study we used an A-16 binding lead sequence, which had previously been obtained from a phage display peptide library (Schellekens et al., 1994). Binding studies with different length variants of this peptide identified a 12mer as a suitable lead compound for our library study. Two incomplete dedicated resin-bound synthetic peptide libraries were generated. Both consisted of 2 X 10(6) 12mers, in which positions were alternately fixed (amino acids identical to the lead sequence) and random. The libraries were screened with mAb A16 and beads with binding peptides were sequenced using Edman degradation. This resulted in a unique peptide binding motif, essentially comprising a 7mer core sequence. Comparison of the sequence of the natural epitope with the binding motif revealed that its sequence was identical to the motif except for one position. Substitution of a methionine in the natural epitope by a tyrosine or a phenylalanine at that position, as dictated by the motif, resulted in a peptide with an affinity for binding to mAb A16 about 50 times higher than that of the natural epitope. Thus, if a lead sequence is available, the use of incomplete, dedicated synthetic peptide libraries provides a fast and powerful tool for the detection of high affinity peptides

THE USE OF DEDICATED PEPTIDE LIBRARIES PERMITS THE DISCOVERY OF HIGH-AFFINITY BINDING PEPTIDES

The motif for peptide binding to monoclonal antibody mAb A16, which is known to be directed against glycoprotein D of Herpes simplex virus type 1, was determined using two dedicated peptide libraries. As a starting point for this study we used an A-16 binding lead sequence, which had previously been obtained from a phage display peptide library (Schellekens et al., 1994). Binding studies with different length variants of this peptide identified a 12mer as a suitable lead compound for our library study. Two incomplete dedicated resin-bound synthetic peptide libraries were generated. Both consisted of 2 X 10(6) 12mers, in which positions were alternately fixed (amino acids identical to the lead sequence) and random. The libraries were screened with mAb A16 and beads with binding peptides were sequenced using Edman degradation. This resulted in a unique peptide binding motif, essentially comprising a 7mer core sequence. Comparison of the sequence of the natural epitope with the binding motif revealed that its sequence was identical to the motif except for one position. Substitution of a methionine in the natural epitope by a tyrosine or a phenylalanine at that position, as dictated by the motif, resulted in a peptide with an affinity for binding to mAb A16 about 50 times higher than that of the natural epitope. Thus, if a lead sequence is available, the use of incomplete, dedicated synthetic peptide libraries provides a fast and powerful tool for the detection of high affinity peptides

Do the health benefits of cycling outweigh the risks? Os benefícios à saúde em andar de bicicleta superam os riscos?

Although from a societal point of view a modal shift from car to bicycle may have beneficial health effects due to decreased air pollution emissions and increased levels of physical activity, shifts in individual adverse health effects such as higher exposure to air pollution and risk of a traffic accident may prevail. We have summarized the literature for air pollution, traffic accidents, and physical activity using systematic reviews supplemented with recent key studies. We quantified the impact on all-cause mortality when 500,000 people would make a transition from car to bicycle for short trips on a daily basis in the Netherlands. We estimate that beneficial effects of increased physical activity are substantially larger (3-14 months gained) than the potential mortality effect of increased inhaled air pollution doses (0.8-40 days lost) and the increase in traffic accidents (5-9 days lost). Societal benefits are even larger because of a modest reduction in air pollution and traffic accidents. On average, the estimated health benefits of cycling were substantially larger than the risks relative to car driving for individuals shifting their mode of transport.<br>Embora uma mudança do uso de carro para bicicleta possa trazer efeitos benéficos para a saúde devido à diminuição da poluição do ar e a um aumento da atividade física, esta mudança também pode trazer efeitos adversos à saúde como exposição à poluição e risco de acidentes de trânsito, os quais podem superar os benefícios. Nós resumimos a literatura sobre poluição do ar, acidentes de trânsito e atividade física, utilizando revisões sistemáticas suplementadas com estudos recentes. Quantificamos também o impacto na causa de mortalidade se 500 mil pessoas fizessem a transição de carro para bicicleta em viagens curtas diárias na Holanda. Estimamos que os efeitos benéficos do aumento da atividade física são substancialmente maiores do que o efeito potencial da mortalidade por inalação de ar poluído e aumento de acidentes de trânsito. Os benefícios sociais são ainda maiores devido a uma modesta redução na poluição do ar e nos acidentes de trânsito. Em média, os benefícios de saúde devido ao uso da bicicleta são substancialmente maiores do que os riscos relativos a dirigir um carro para pessoas em transição do modo de transporte