Changes In Protein Molecular Structure Research Articles

Conformational control over proton-coupled electron transfer in metalloenzymes.

From the reduction of dinitrogen to the oxidation of water, thechemical transformations catalysed by metalloenzymes underlie global geochemical and biochemical cycles. These reactions represent some of the most kinetically and thermodynamically challenging processes knownand require the complex choreography of the fundamental building blocks of nature, electrons and protons, to be carried out with utmost precision and accuracy. The rate-determining step of catalysis in many metalloenzymes consists of aprotein structural rearrangement, suggestingthat nature has evolved to leverage macroscopic changes in protein molecularstructure to control subatomicchanges in metallocofactor electronicstructure. The proton-coupled electron transfermechanisms operative in nitrogenase, photosystem II and ribonucleotide reductase exemplify this interplay between molecular and electronic structural control. We present the culmination of decades of study on each of these systems and clarify what is known regarding the interplay between structural changesand functional outcomes in these metalloenzyme linchpins.

PSXII-5 Feed processing-induced changes in protein molecular structure in relation to nutrient utilization and availability of warm-season Sorghum grain (Sorghum bicolor) in ruminants

Abstract The objective of this study was reveal heat related processing (HP) induced changes in protein molecular structure in relation to nutrient utilization and availability of warm-season sorghum grain (Sorghum bicolor) in dairy cows. Three new warm-season genotypes of sorghum grain (Sorghum bicolor) were studied. The nutrient utilization and availability of sorghum grain (Sorghum bicolor) in dairy cows include: protein subfractions, energy values, rumen degradation, and intestinal digestibility of rumen undegraded protein. The protein structure change on molecular level were revealed with cutting edge non-invasive vibrational ATR-FTIR molecular spectroscopy. The warm-season sorghum grains were either maintained in their raw state (as control) or treated with for 80 min at 121°C with the Lindberg/Blue M™. The RCBD data were analyzed using SAS9.4 with Mixed model procedure. Tukey method was used for mean separation. The results showed that compared with the control, the HP treatment altered (P < 0.05) nutrient profiles and utilization and availability in dairy cows and increased (P < 0.05) metabolizable energy and net energy values in dairy cows. The HP treatment also altered (P < 0.05) the protein molecular structure profile of the warm-season sorghum grain. It increased (P < 0.05) the ratio of protein Amide I and Amide II height and decreased (P < 0.05) the ratio of α-helix to β-sheet. In conclusion, the HP treatment altered molecular structure and nutrient profiles without negatively affecting the nutritive value and digestion of warm-season sorghum grain. The molecular spectral profiles revealed by rapid and non-invasive ATR-FTIR molecular spectroscopy could be used as a fast predictor for the warm-season sorghum grain utilization and digestion in dairy cows.

Application of FT/IR-ATR vibrational spectroscopy to reveal protein molecular structure of feedstock and co-products from Canadian and Chinese canola processing in relation to microorganism bio-degradation and enzyme bio-digestion

The principal objective of this study was to apply FT/IR-ATR vibrational spectroscopy to inspect the relationship between rumen dry matter (DM) and protein degradation, rumen undegraded protein (RUP) intestinal digestion and processing induced protein molecular structure changes in feedstock (canola oil seeds) and co-products (canola meal) from bio-oil processing from different crushing plants in Canada and China. The rumen DM and protein degradation, rumen undegraded protein intestinal digestion and protein molecular structure affected by bio-oil processing were examined using in situ, three step in vitro digestion and Fourier transform infrared (FT/IR) molecular spectroscopy techniques, respectively. The results showed that the protein molecular structure; α-helix height and α-helix to β-sheet height ratio had a close association with rumen DM and protein degradation and rumen undegraded protein intestinal digestibility. Multiple regression analyses showed that protein β-sheet height and α-helix to β-sheet height ratio spectral intensity can be used to predict rumen DM and protein degradation, while intestinal digestibility of rumen undegraded protein can be predicted by α-helix height and β-sheet height. In conclusion, the co-product canola meal from bio-oil processing is a good source of intestinally digestible protein. Rumen DM and protein degradation and intestinal digestibility of rumen undegraded protein are related to the protein molecular structures of the co-products affected by changes during bio-oil processing.

Protein molecular structure in relation to predicted biodegradation and nutrient supply of feedstocks and co-products from bio-oil processing with CNCPS system: Comparison Crusher Plants within Canada and within China as well as between Canada and China

Recently, rapid non-invasive advanced vibrational molecular spectroscopy has been developed to detect tissue inherent molecular structure. However, this advanced technique is seldom known by animal scientists and seldom used to study feed molecular structure in relation to nutrient utilization and availability in animals. The objectives of this study were to 1) detect the interactive association between the processing-induced protein molecular structure changes and biodegradation and intestinal digestion in ruminants using advanced vibrational molecular spectroscopy, and 2) develop a model to predict protein and carbohydrate degradation and digestions based on feed inherent protein molecular structure. The feed used for this study were various sources of feedstock (oil seeds) and co-products (canola meal, canola pellets) from ten different crushing plants in Canada and China with multi-source samples from each crushing plant. The predictable protein and carbohydrate degradable sub-fractions and nutrient supply of sub-fractions to dairy cows were evaluated with the updated Cornell Net Carbohydrate and Protein System (CNCPS 6.5). The protein molecular structure was revealed using advanced vibrational molecular spectroscopy (FT/IR-ATR). The molecular structure spectral analyses were carried out using uni- and multi-variate molecular spectral analyses. The model variable selection was carried out using SAS with a Stepwise option. The results showed that protein molecular structure spectral characteristics could be used to predict CNCPS protein and carbohydrate nutrient supply to dairy cows. Strong positive correlation was found in canola meal between rumen degraded PA2 and amide I area (r = 0.67, P < 0.001), amide I height (r = 0.73, P < 0.001), and α-helix height (r = 0.83, P < 0.001). RDPB2 was negatively correlated with α-helix height (r = −0.69, P < 0.001). Moreover, TRDC was negatively correlated with amide I area (r=-0.64, P < 0.001), amide I height (r = −0.65, P < 0.001), and α-helix height (r = −0.62, P < 0.001). It was concluded that protein and carbohydrate degradable and undegradable sub-fractions had interactive associations with the processing-induced protein molecular structure changes in co-products from bio-oil processing.

Effects of heat processing methods on protein subfractions and protein degradation kinetics in dairy cattle in relation to protein molecular structure of barley grain using advanced molecular spectroscopy

The objectives of this study were: (1) to investigate the effect of three different heat processing methods on chemical profile, CNCPS protein subfraction, rumen degradation characteristics, and protein molecular structure of barley grain (CDC Meredith) using Fourier transform infrared attenuated total reflectance advanced molecular spectroscopy; (2) to detect association between protein degradation and availability and protein molecular structure profiles in dairy cows. The grains were kept as raw (control) or heated in an air-draft oven at 120 °C for 60min or in an autoclave at 120 °C for 60min or in a microwave at 900w for 5min. The results showed that autoclave heating decreased the ruminal effective degradability and increased the intestinal digestion of protein. The molecular spectroscopy was able to identify heating-induced changes in protein molecular structure, revealing that dry heating increased the amide I to II area ratio when compared with control. The α-helix to β-sheet ratio was greater in microwave heating than autoclave heating, suggesting protein damage in microwave-heated grains. The autoclave heating decreased the effective degradability of protein while increased the intestinal digestion of rumen undegradable protein. Protein subfractions, rumen degradable, undegradable and intestinal digestible protein fractions and degradation characteristics could be predicted by amide I area or α-helix.

589 Heat-induced changes in protein molecular structure associated with rumen degradation of oat grains in dairy cows detecting by vibrational molecular spectroscopy

589 Heat-induced changes in protein molecular structure associated with rumen degradation of oat grains in dairy cows detecting by vibrational molecular spectroscopy

Structural changes on a molecular basis of canola meal by conditioning temperature and time during pelleting process in relation to physiochemical (energy and protein) properties relevant to ruminants.

The objectives of this study were: (1) To investigate the effects of conditioning temperature (70, 80, 90°C), time (30, 60 sec), and interaction (temperature × time) during the pelleting process on internal protein molecular structure changes of the co-products; (2) To identify differences in protein molecular structures among pellets that were processed under different conditions, and between unprocessed mash and pellets; 3) To quantify protein molecular structure changes in relation to predicted energy and protein utilization in dairy cows. The final goal of this program was to show how processing conditions changed internal feed structure on a molecular basis and how molecular structure changes induced by feed processing affected feed milk value in dairy cows. The hypothesis in this study was that processing-induced protein inherent structure changes affected energy and protein availability in dairy cattle and the sensitivity and response of protein internal structure to the different pelleting process conditions could be detected by advanced molecular spectroscopy. The protein molecular structures, amides I and II, amide I to II ratios, α-helix structure, β-sheet structure, and α to β structure ratios, were determined using the advanced vibrational molecular spectroscopy (ATR-FT/IR). The energy values were determined using NRC2001 summary approach in terms of total digestible nutrients, metabolizable and net energy for lactation. The protein and carbohydrate subfactions that are related to rumen degradation characteristics and rumen undegraded protein supply were determined using updated CNCPS system. The experiment design was a RCBD and the treatment design was a 3x2 factorial design. The results showed that pelleting induced changes in protein molecular structure. The sensitivity and response of protein inherent structure to the pelleting depended on the conditioning temperature and time. The protein molecular structure changes were correlated (P < 0.05) with energy values and protein subfractions of the pelleted co-product. The results indicated that the protein internal molecular structure had significant roles in determining energy and protein nutritive values in dairy cows. Multi-regression study with model variables selection showed that the energy and protein profiles in pelleted co-products could be predicted with the protein molecular structure profiles. This approach provides us a relatively new way to estimate protein value in dairy cows based on internal protein molecular structure profile.

The inter-relationship between processing-induced molecular structure features and metabolic and digestive characteristics in hulled and hulless barley (Hordeum vulgare) grains with altered carbohydrate traits.

The present study aimed to determine the microwave irradiation (MIR)-induced changes in protein molecular structures in barley (Hordeum vulgare) grains in relation to the truly absorbable protein nutrient supply to ruminant livestock systems. Samples from hulled and hulless cultivars of barley, harvested in consecutive years from four replicate plots, were evaluated. The samples were either kept raw or were irradiated with microwaves for 3 min (MIR3) or 5 min (MIR5). The truly absorbable protein nutrient supply to ruminant livestock systems was evaluated using the DVE/OEB system (DVE, truly absorbed protein in the small intestine; OEB, degraded protein balance). Molecular structure changes as a result of processing were revealed by vibrational molecular spectroscopy in the mid-infrared electromagnetic radiation region. Compared to the raw samples, MIR processing decreased (P < 0.05) the truly absorbable microbial crude protein and increased (P < 0.05) the truly absorbable rumen undegraded protein and endogenous protein supply without affecting the total truly absorbed protein supply to the small intestine (DVE) and degraded protein balance (OEB) in ruminant livestock systems. Changes in protein molecular structure (spectral intensities) were highly correlated with the changes in the truly absorbed protein nutrient supply to ruminant livestock systems. The results of the present study show that the changes in protein molecular structure as a result of MIR feed processing were associated with the truly absorbed protein supply to ruminant livestock systems. © 2016 Society of Chemical Industry.

Association of Bio-energy Processing-Induced Protein Molecular Structure Changes with CNCPS-Based Protein Degradation and Digestion of Co-products in Dairy Cows.

The primary objective of this study was to develop a model to predict Cornell Net Carbohydrate Protein System (CNCPS) protein degradation and digestion based on protein molecular structure changes induced by bio-energy processing in different types of co-products (CoPR, CoPC, CoPS = co-products from bioprocessing of rapeseed, canola seed, and soybean, respectively). The results showed that the inherent structure changes induced by the processing had a close relationship with CNCPS predicted protein degradable, undegradable, and digestible contents. The amide I to II ratio and α-helix to β-sheet ratio could be used to predict total degradable protein (R(2) = 0.99, RSD = 0.84, P < 0.001). Total CNCPS intestinal digestible protein could be predicted by protein structure α-helix to β-sheet ratio (R(2) = 0.93, RSD = 0.33, P < 0.001). In conclusion, the processing-induced protein molecular structure changes were highly linked to protein nutritive value of the co-products and could be used as predictors for CNCPS protein degradation and digestion in dairy cattle.

Moist and dry heating-induced changes in protein molecular structure, protein subfractions, and nutrient profiles in camelina seeds

The objectives of the present study were to investigate the nutritive value of camelina seeds (Camelina sativa L. Crantz) in ruminant nutrition and to use molecular spectroscopy as a novel technique to quantify the heat-induced changes in protein molecular structures in relation to protein digestive behavior in the rumen and intestine of dairy cattle. In this study, camelina seeds were used as a model for feed protein. The seeds were kept as raw (control) or heated in an autoclave (moist heating) or in an air-draft oven (dry heating) at 120°C for 60 min. The parameters evaluated were (1) chemical profiles, (2) Cornell Net Protein and Carbohydrate System protein subfractions, (3) nutrient digestibilities and estimated energy values, (4) in situ rumen degradation and intestinal digestibility, and (5) protein molecular structures. Compared with raw seeds, moist heating markedly decreased (52.73 to 20.41%) the content of soluble protein and increased (2.00 to 9.01%) the content of neutral detergent insoluble protein in total crude protein (CP). Subsequently, the rapidly degradable Cornell Net Protein and Carbohydrate System CP fraction markedly decreased (45.06 to 16.69% CP), with a concomitant increase in the intermediately degradable (45.28 to 74.02% CP) and slowly degradable (1.13 to 8.02% CP) fractions, demonstrating a decrease in overall protein degradability in the rumen. The in situ rumen incubation study revealed that moist heating decreased (75.45 to 57.92%) rumen-degradable protein and increased (43.90 to 82.95%) intestinal digestibility of rumen-undegradable protein. The molecular spectroscopy study revealed that moist heating increased the amide I-to-amide II ratio and decreased α-helix and α-helix-to-β-sheet ratio. In contrast, dry heating did not significantly change CP solubility, rumen degradability, intestinal digestibility, and protein molecular structures compared with the raw seeds. Our results indicated that, compared with dry heating, moist heating markedly changed protein chemical profiles, protein subfractions, rumen protein degradability, and intestinal digestibility, which were associated with changes in protein molecular structures (amide I-to-amid II ratio and α-helix-to-β-sheet ratio). Moist heating improved the nutritive value and utilization of protein in camelina seeds compared with dry heating.

Detect the sensitivity and response of protein molecular structure of whole canola seed (yellow and brown) to different heat processing methods and relation to protein utilization and availability using ATR-FT/IR molecular spectroscopy with chemometrics

The objectives of this experiment were to detect the sensitivity and response of protein molecular structure of whole canola seed to different heat processing [moisture (autoclaving) vs. dry (roasting) heating] and quantify heat-induced protein molecular structure changes in relation to protein utilization and availability. In this study, whole canola seeds were autoclaved (moisture heating) and dry (roasting) heated at 120°C for 1h, respectively. The parameters assessed included changes in (1) chemical composition profile, (2) CNCPS protein subfractions (PA, PB1, PB2, PB3, PC), (3) intestinal absorbed true protein supply, (4) energy values, and (5) protein molecular structures (amide I, amide II, ratio of amide I to II, α-helix, β-sheet, ratio of α-helix to β-sheet). The results showed that autoclave heating significantly decreased (P<0.05) but dry heating increased (P<0.05) the ratio of protein α-helix to β-sheet (with the ratios of 1.07, 0.95, 1.10 for the control (raw), autoclave heating and dry heating, respectively). The multivariate molecular spectral analyses (PCA, CLA) showed that there were significantly molecular structural differences in the protein amide I and II fingerprint region (ca. 1714–1480cm−1) among the control, autoclave and dry heating. These differences were indicated by the form of separate class (PCA) and group of separate ellipse (CLA) between the treatments. The correlation analysis with spearman method showed that there were significantly and highly positive correlation (P<0.05) between heat-induced protein molecular structure changes in terms of α-helix to β-sheet ratios and in situ protein degradation and significantly negative correlation between the protein α-helix to β-sheet ratios and intestinal digestibility of undegraded protein. The results indicated that heat-induced changes of protein molecular structure revealed by vibration molecular spectroscopy could be used as a potential predictor to protein degradation and intestinal protein digestion of whole canola seed. Future study is needed to study response and impact of heat processing to each inherent layer of canola seed from outside to inside tissues and between yellow canola and brown canola.

In‐depth study of the protein molecular structures of different types of dried distillers grains with solubles and their relationship to digestive characteristics

Dried distillers grains with solubles (DDGS) have been extensively utilised in ruminant rations in western Canada and USA, and it is important to ensure their consistent quality. Traditional chemical methods do not consider the inherent structural changes of feed ingredients. Synchrotron-based Fourier transform infrared microspectroscopy (SFTIRM) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) have been utilised to detect the changes in molecular structure of several feedstuffs (e.g. barley, flaxseed and alfalfa). However, similar structural information is lacking for DDGS. The objectives of this study were to identify differences in protein molecular structures between different grains (wheat, triticale and corn) and DDGS (wheat DDGS, triticale DDGS, corn DDGS and wheat and corn blend DDGS) using SFTIRM and DRIFT and to reveal the relationship between changes in protein molecular structure and the digestive characteristics of the protein in DDGS when fed to dairy cattle. The protein molecular structure studies showed significant decreases (P < 0.01) in the amide I to amide II ratio and the α-helix to β-sheet ratio between grains and their DDGS. Protein digestive characteristics were correlated with protein molecular structures in grains and DDGS, and prediction equations were established to estimate protein digestive characteristics of DDGS using protein molecular structure parameters. For the DVE/OEB-1994 model, one of the best prediction equations was for truly absorbed protein in the small intestine (DVE) = 296.17 - 38.98 × the amide I to amide II ratio (R(2) = 0.72). For the NRC-2001 system, one of the best prediction equations was for metabolisable protein (MP) = 300.96 - 43.32 × the amide I to amide II ratio (R(2) = 0.76). Protein molecular structure varies between different DDGS and their original grains, and this variation is associated with the digestive characteristics of the proteins in the DDGS and their original grains.

Dry and moist heating-induced changes in protein molecular structure, protein subfraction, and nutrient profiles in soybeans

Heat processing has been used to improve protein utilization and availability of animal nutrition. However, to date, few studies exist on heat-induced protein molecular structure changes on a molecular basis. The aims of this study were to use molecular spectroscopy as a novel approach to determine heat-induced protein molecular structure changes affected by moist and dry heating and quantify protein molecular structures and nutritive value in the rumen and intestine in dairy cattle. In this study, soybean was used as a model for feed protein and was autoclaved at 120°C for 1h (moist heating) and dry heated at 120°C for 1h. The parameters assessed in this study included protein structure α-helix and β-sheet and their ratio, protein subfractions associated with protein degradation behaviors, intestinal protein availability, and energy values. The results show that heat treatments changed the protein molecular structure. Both dry and moist heating increased the amide I-to-amide II ratio. However, for the protein α-helix-to-β-sheet ratio, moist heating decreased but dry heating increased the ratio. Compared with dry heating, moist heating dramatically changed the chemical and nutrient profiles of soybean seed. It greatly decreased soluble crude protein, nonprotein nitrogen, and increased neutral detergent insoluble protein. Both dry and moist heating treatments did not alter digestible nutrients and energy values. Heating tended to decrease the nonprotein nitrogen fraction (soluble and rapidly degradable protein fraction) and true protein 1 fraction (fast-degradable protein fraction). Conversely, the true protein 3 fraction (slowly degradable fraction) significantly increased. The in situ rumen study showed that moist heating decreased protein rumen degradability and increased intestinal digestibility of rumen-undegradable protein. Compared with the raw soybeans, dry heating did not affect rumen degradability and intestinal digestibility. In conclusion, compared with dry heating, moist heating dramatically affected the nutrient profile, protein subfractions, rumen degradability, intestinal digestibility, and protein molecular structure (amide I-to-II ratio; α-helix-to-β-sheet ratio). The sensitivity of soybean seed to moist heating was much higher than that to dry heating in terms of the structure and nutrient profile changes.