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SAXSMoW (SAXS Molecular Weight) is an online platform widely used over the past few years for determination of molecular weights of proteins in dilute solutions. The scattering intensity retrieved from small‐angle X‐ray scattering (SAXS) raw data is the sole input to SAXSMoW for determination of molecular weights of proteins in liquid. The current updated SAXSMoW version 3.0 determines the linear dependence of the true protein volume on their apparent protein volume, based on SAXS curves calculated for 67,000 protein structures selected from the Protein Data Bank. SAXSMoW 3.0 was tested against 43 experimental SAXS scattering curves from proteins with known molecular weights. Our results demonstrate that most of the molecular weights determined for the nonglycosylated and also for the glycosylated proteins are in good agreement with their expected molecular weights. Additionally, the average discrepancies between the calculated molecular weights and their nominal values for glycosylated proteins are similar to those for nonglycosylated ones. [ABSTRACT FROM AUTHOR]

Background: Caries constitute an infectious disease that result from the interaction of bacteria with the host and the oral environment. Streptococcus mutans (S. mutans) represents the main bacterium that causes caries. The ability of S. mutans to form biofilms in the oral cavity is influenced by daily nutrient intake. This study of bacterial biofilm proteins can be used in the manufacture of kits for the detection of infectious diseases such as caries in the oral cavity. A biomarker is required for the manufacture of the detection kit. Consequently, research must first be conducted to determine the molecular weight and density of S. mutans biofilm proteins induced by several different daily nutrients, namely; 5% glucose, 5% lactose, soy protein and 5% iron. Purpose: This study aimed to analyse the density of S. mutans biofilm protein induced by 5% glucose, 5% lactose, soy protein, and 5% iron. Methods: The density of the S. mutans biofilm protein bands induced were measured using EZ Imager Gel DocTM software. Results: A band of biofilm protein (61.7 kDa) was obtained from S. mutans induced by 5% glucose, four bands of biofilm protein (180 kDa; 153,9 kDa; 43,9 kDa; 37,5 kDa) from 5% lactose induction and seven bands of biofilm protein (157,9 kDa; 86,6 kDa; 66,5 kDa; 50,1 kDa; 37,9 kDa; 32,3 kDa; 29,4 kDa) from soy protein induction. In contrast, S. mutans induced by 5% iron did not show any protein bands. The proteins that result from each inducer are of differing densities. Conclusion: The protein bands from each inducer are of different densities which can be used in the further test to make a biomarker for dental caries detection kits.

Hideaki Okawada, Yuta Saito, Shigehiro Iwabuchi, Shotaro Kosuge, Haruo Takahashi, Hidetoshi Onda, Masahiro Kito Department of Ophthalmology, Showa University, Tokyo, Japan Purpose: Vascular endothelial growth factor (VEGF) plays an important role in branch retinal vein occlusion (BRVO) with cystoid macular edema (CME). Monitoring changes in VEGF is crucial for evaluating treatment but requires vitreous or aqueous humor sampling, which hampers its clinical application. We investigated the correlation between VEGF and protein concentration in the aqueous humor (flare) and whether this could be used to monitor treatment-related VEGF changes. Design: This retrospective observational study involved 19 previously untreated patients with BRVO. Aqueous humor was obtained, and intravitreal ranibizumab (IVR) injection was administered to these patients. The correlation between VEGF and flare, central retinal thickness (CRT), and best-corrected visual acuity (BCVA) was investigated. Differences in these values were considered between pre-IVR and 1 week and 1–3 months post-IVR. Moreover, in patients with recurrence who received additional IVR, further changes in VEGF were examined. Main outcome measures: The end point of this study was BCVA, flare, and CRT at the fovea. Results: Significant improvement was seen in BCVA and CRT at all time points and in Flare at 1 vs 3 months post-IVR; nevertheless, additional IVR was necessary in 94% of cases. In a patient with recurrence, CRT did not improve, even though VEGF decreased. Conclusion: Flare may be effective for estimating VEGF levels in aqueous humor pre-IVR. Inflammation-related molecules other than VEGF may be related to recurrence. Keywords: aqueous humor, branch retinal vein occlusion, flare, protein density, ranibizumab, vascular endothelial growth factor

Abstract: Biological membranes undergo constant shape remodeling involving the formation of highly curved structures. The lipid bilayer represents the fundamental architecture of the cellular membrane with its shapes determined by the Helfrich curvature bending energy. However, the dynamics of bilayer shape transitions, especially their modulation by membrane proteins, and the resulting shape instabilities, are still not well understood. Here, we review in a unifying manner several theories that describe the fluctuations (i.e. undulations) of bilayer shapes as well as their local coupling with lipid or protein density variation. The coupling between local membrane curvature and lipid density gives rise to a ‘slipping mode’ in addition to the conventional ‘bending mode’ for damping the membrane fluctuation. This leads to a number of interesting experimental phenomena regarding bilayer shape dynamics. More importantly, curvature-inducing proteins can couple with membrane shape and eventually render the membrane unstable. A criterion for membrane shape instability is derived from a linear stability analysis. The instability criterion reemphasizes the importance of membrane tension in regulating the stability and dynamics of membrane geometry. Recent progresses in understanding the role of membrane tension in regulating dynamical cellular processes are also reviewed. Protein density is emphasized as a key factor in regulating membrane shape transitions: a threshold density of curvature coupling proteins is required for inducing membrane morphology transitions. [Copyright &y& Elsevier]

The mass density of proteins is a relevant basic biophysical quantity. It is also a useful input parameter, for example, for three-dimensional structure determination by protein crystallography and studies of protein oligomers in solution by analytic ultracentrifugation. We have performed a critical analysis of published, theoretical, and experimental investigations about this issue and concluded that the average density of proteins is not a constant as often assumed. For proteins with a molecular weight below 20 kDa, the average density exhibits a positive deviation that increases for decreasing molecular weight. A simple molecular-weight-depending function is proposed that provides a more accurate estimate of the average protein density. [ABSTRACT FROM AUTHOR]

A high-protein diet can reduce body weight and increase insulin sensitivity, but whether the type of dietary protein affects these outcomes is unknown. We hypothesized that feeding insulin-resistant rats a high-protein diet (32%) containing whey protein concentrate (WPC) would reduce body weight and tissue lipid levels and increase insulin sensitivity more than a diet containing red meat (RM). Rats were fed a high-fat diet (300 g fat/kg diet) for 9 wk, then switched to a diet containing either 80 or 320 g protein/kg diet, provided by either WPC or RM, for 6 wk (n = 8). The rats were then killed after overnight food deprivation. High dietary protein reduced energy intake (P < 0.001) and visceral (P < 0.001), subcutaneous (P < 0.001), and carcass fat (P < 0.05). Increasing the dietary density of WPC, but not of RM, reduced body weight gain by 4% (P < 0.001). Dietary WPC also reduced plasma insulin concentration by 40% (P < 0.05) and increased insulin sensitivity, compared to RM (P < 0.05). These findings support the conclusions that a high-protein diet reduces energy intake and adiposity and that whey protein is more effective than red meat in reducing body weight gain and increasing insulin sensitivity. [ABSTRACT FROM AUTHOR]

SAXSMoW (SAXS Molecular Weight) is an online platform widely used over the past few years for determination of molecular weights of proteins in dilute solutions. The scattering intensity retrieved from small-angle X-ray scattering (SAXS) raw data is the sole input to SAXSMoW for determination of molecular weights of proteins in liquid. The current updated SAXSMoW version 3.0 determines the linear dependence of the true protein volume on their apparent protein volume, based on SAXS curves calculated for 67,000 protein structures selected from the Protein Data Bank. SAXSMoW 3.0 was tested against 43 experimental SAXS scattering curves from proteins with known molecular weights. Our results demonstrate that most of the molecular weights determined for the nonglycosylated and also for the glycosylated proteins are in good agreement with their expected molecular weights. Additionally, the average discrepancies between the calculated molecular weights and their nominal values for glycosylated proteins are similar to those for nonglycosylated ones., (© 2021 The Protein Society.)

Dietary guidelines suggest consuming a mixed-protein diet, consisting of high-quality animal, dairy, and plant-based foods. However, current data on the distribution and the food sources of protein intake in a free-living, representative sample of US adults are not available. Data from the National Health and Nutrition Examination Survey (NHANES), 2007-2010, were used in these analyses (n = 10,977, age ≥ 19 years). Several US Department of Agriculture (USDA) databases were used to partition the composition of foods consumed into animal, dairy, or plant components. Mean ± SE animal, dairy, and plant protein intakes were determined and deciles of usual intakes were estimated. The percentages of total protein intake derived from animal, dairy, and plant protein were 46%, 16%, and 30%, respectively; 8% of intake could not be classified. Chicken and beef were the primary food sources of animal protein intake. Cheese, reduced-fat milk, and ice cream/dairy desserts were primary sources of dairy protein intake. Yeast breads, rolls/buns, and nuts/seeds were primary sources of plant protein intake. This study provides baseline data for assessing the effectiveness of public health interventions designed to alter the composition of protein foods consumed by the American public.