Isomaltulose stands out for its low glycemic index and caries-resistant properties,and shows great potential for applications in the food and medical fields.Belonging to the glycoside hydrolase family GH13,sucrose iso...Isomaltulose stands out for its low glycemic index and caries-resistant properties,and shows great potential for applications in the food and medical fields.Belonging to the glycoside hydrolase family GH13,sucrose isomerase is capable of converting sucrose to isomaltulose.The sucrose isomerase from Pantoea dispersa UQ68J(PdSI)is favored for its high conversion rates.However,poor thermostability limits its application in industrial production.To enhance the thermostability of PdSI,we combined sequence analysis and computer-aided design to identify and exclude key sites that might affect catalytic activity,and then screened 14 candidate mutants for point mutation validation.During the study,single-point mutants M62E,V105I,N109H,D232P,V447E and S481M demonstrated improved thermostability in preliminary experiments.Among them,the mutant V447E performed particularly well,with a 1.38-fold increase in half-life at 40℃ compared to the wild type,and showed an increase in the optimal temperature from 30℃ to 35℃.Further combined mutation studies revealed that mutant V447E/D232P showed better thermostability.Compared with the wild type,mutant V447E/D232P increased the optimal temperature by 5℃,and its half-life at 40℃ was prolonged by 1.52-fold.The results of molecular dynamics simulations further confirmed the low root-mean-square fluctuations of V447E and V447E/D232P compared with the wild type,indicating a significant enhancement in structural stability.This study offers a reference for improving the thermostability modification of sucrose isomerase and promotes the industrial application of isomaltulose.展开更多
N-kink soliton and high-order synchronized breather solutions for potential Kadomtsev-Petviashvili equation are derived by means of the Hirota bilinear method,and the limit process of high-order synchronized breathers...N-kink soliton and high-order synchronized breather solutions for potential Kadomtsev-Petviashvili equation are derived by means of the Hirota bilinear method,and the limit process of high-order synchronized breathers are shown.Furthermore,M-lump solutions are also presented by taking the long wave limit.Additionally,a family of semi-rational solutions with elastic collision are generated by taking a long-wave limit of only a part of exponential functions,their interaction behaviors are shown by three-dimensional plots and contour plots.展开更多
The Hirota equation can be used to describe the wave propagation of an ultrashort optical field.In this paper,the multi-component Hirota(alias n-Hirota,i.e.n-component third-order nonlinear Schrodinger)equations with ...The Hirota equation can be used to describe the wave propagation of an ultrashort optical field.In this paper,the multi-component Hirota(alias n-Hirota,i.e.n-component third-order nonlinear Schrodinger)equations with mixed non-zero and zero boundary conditions are explored.We employ the multiple roots of the characteristic polynomial related to the Lax pair and modified Darboux transform to find vector semi-rational rogon-soliton solutions(i.e.nonlinear combinations of rogon and soliton solutions).The semi-rational rogon-soliton features can be modulated by the polynomial degree.For the larger solution parameters,the first m(m<n)components with non-zero backgrounds can be decomposed into rational rogons and grey-like solitons,and the last n-m components with zero backgrounds can approach bright-like solitons.Moreover,we analyze the accelerations and curvatures of the quasi-characteristic curves,as well as the variations of accelerations with the distances to judge the interaction intensities between rogons and grey-like solitons.We also find the semi-rational rogon-soliton solutions with ultrahigh amplitudes.In particular,we can also deduce vector semi-rational solitons of the ncomponent complex mKdV equation.These results will be useful to further study the related nonlinear wave phenomena of multi-component physical models with mixed background,and even design the related physical experiments.展开更多
Optical fibers are seen in the optical sensing and optical fiber communication. Simultaneous propagation of optical pulses in an inhomogeneous optical fiber is described by a coupled time-dependent coefficient fourth-...Optical fibers are seen in the optical sensing and optical fiber communication. Simultaneous propagation of optical pulses in an inhomogeneous optical fiber is described by a coupled time-dependent coefficient fourth-order nonlinear Schr?dinger system, which is discussed in this paper. For such a system, we work out the Lax pair, Darboux transformation, and corresponding vector semi-rational nonautonomous rogue wave solutions. When the group velocity dispersion(GVD) and fourth-order dispersion(FOD) coefficients are the constants, we exhibit the first-and second-order vector semirational rogue waves which are composed of the four-petalled rogue waves and eye-shaped breathers. Both the width of the rogue wave along the time axis and temporal separation between the adjacent peaks of the breather decrease with the GVD coefficient or FOD coefficient. With the GVD and FOD coefficients as the linear, cosine, and exponential functions, we respectively present the first-and second-order periodic vector semi-rational rogue waves, first-and second-order asymmetry vector semi-rational rogue waves, and interactions between the eye-shaped breathers and the composite rogue waves.展开更多
基金supported by the National Natural Science Foundation of China[32430081,32272264]the Jiangsu Provincial Key Research and Development Program[BE2023686]the Fundamental Research Funds for the Central Universities[JUSRP122012].
文摘Isomaltulose stands out for its low glycemic index and caries-resistant properties,and shows great potential for applications in the food and medical fields.Belonging to the glycoside hydrolase family GH13,sucrose isomerase is capable of converting sucrose to isomaltulose.The sucrose isomerase from Pantoea dispersa UQ68J(PdSI)is favored for its high conversion rates.However,poor thermostability limits its application in industrial production.To enhance the thermostability of PdSI,we combined sequence analysis and computer-aided design to identify and exclude key sites that might affect catalytic activity,and then screened 14 candidate mutants for point mutation validation.During the study,single-point mutants M62E,V105I,N109H,D232P,V447E and S481M demonstrated improved thermostability in preliminary experiments.Among them,the mutant V447E performed particularly well,with a 1.38-fold increase in half-life at 40℃ compared to the wild type,and showed an increase in the optimal temperature from 30℃ to 35℃.Further combined mutation studies revealed that mutant V447E/D232P showed better thermostability.Compared with the wild type,mutant V447E/D232P increased the optimal temperature by 5℃,and its half-life at 40℃ was prolonged by 1.52-fold.The results of molecular dynamics simulations further confirmed the low root-mean-square fluctuations of V447E and V447E/D232P compared with the wild type,indicating a significant enhancement in structural stability.This study offers a reference for improving the thermostability modification of sucrose isomerase and promotes the industrial application of isomaltulose.
基金supported by the NSF of China under Grant No.12001377,Grant No.11671219 and Grant No.12071304.
文摘N-kink soliton and high-order synchronized breather solutions for potential Kadomtsev-Petviashvili equation are derived by means of the Hirota bilinear method,and the limit process of high-order synchronized breathers are shown.Furthermore,M-lump solutions are also presented by taking the long wave limit.Additionally,a family of semi-rational solutions with elastic collision are generated by taking a long-wave limit of only a part of exponential functions,their interaction behaviors are shown by three-dimensional plots and contour plots.
基金supported by the National Natural Science Foundation of China(Nos.11925108 and 11731014)
文摘The Hirota equation can be used to describe the wave propagation of an ultrashort optical field.In this paper,the multi-component Hirota(alias n-Hirota,i.e.n-component third-order nonlinear Schrodinger)equations with mixed non-zero and zero boundary conditions are explored.We employ the multiple roots of the characteristic polynomial related to the Lax pair and modified Darboux transform to find vector semi-rational rogon-soliton solutions(i.e.nonlinear combinations of rogon and soliton solutions).The semi-rational rogon-soliton features can be modulated by the polynomial degree.For the larger solution parameters,the first m(m<n)components with non-zero backgrounds can be decomposed into rational rogons and grey-like solitons,and the last n-m components with zero backgrounds can approach bright-like solitons.Moreover,we analyze the accelerations and curvatures of the quasi-characteristic curves,as well as the variations of accelerations with the distances to judge the interaction intensities between rogons and grey-like solitons.We also find the semi-rational rogon-soliton solutions with ultrahigh amplitudes.In particular,we can also deduce vector semi-rational solitons of the ncomponent complex mKdV equation.These results will be useful to further study the related nonlinear wave phenomena of multi-component physical models with mixed background,and even design the related physical experiments.
基金Project supported by the BUPT Excellent Ph.D.Students Foundation(Grant No.CX2019201)the National Natural Science Foundation of China(Grant Nos.11772017 and 11805020)+1 种基金the Fund of State Key Laboratory of Information Photonics and Optical Communications(Beijing University of Posts and Telecommunications),China(Grant No.IPOC:2017ZZ05)the Fundamental Research Funds for the Central Universities of China(Grant No.2011BUPTYB02)。
文摘Optical fibers are seen in the optical sensing and optical fiber communication. Simultaneous propagation of optical pulses in an inhomogeneous optical fiber is described by a coupled time-dependent coefficient fourth-order nonlinear Schr?dinger system, which is discussed in this paper. For such a system, we work out the Lax pair, Darboux transformation, and corresponding vector semi-rational nonautonomous rogue wave solutions. When the group velocity dispersion(GVD) and fourth-order dispersion(FOD) coefficients are the constants, we exhibit the first-and second-order vector semirational rogue waves which are composed of the four-petalled rogue waves and eye-shaped breathers. Both the width of the rogue wave along the time axis and temporal separation between the adjacent peaks of the breather decrease with the GVD coefficient or FOD coefficient. With the GVD and FOD coefficients as the linear, cosine, and exponential functions, we respectively present the first-and second-order periodic vector semi-rational rogue waves, first-and second-order asymmetry vector semi-rational rogue waves, and interactions between the eye-shaped breathers and the composite rogue waves.
