1. Reorganization and caging of DPPC, DPPE, DPPG, and DPPS monolayers caused by dimethylsulfoxide observed using Brewster angle microscopy
Xiangke Chen,Zishuai Huang,Heather C Allen,Hardy Castada,Wei Hua Langmuir . 2010 Dec 21;26(24):18902-8. doi: 10.1021/la102842a.
The interaction between dimethylsulfoxide (DMSO) and phospholipid monolayers with different polar headgroups was studied using "in situ" Brewster angle microscopy (BAM) coupled to a Langmuir trough. For a 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) monolayer, DMSO was shown to significantly impact the structure of the liquid expanded (LE) and gaseous phases. The domains reorganized to much larger domain structures. Domains in the liquid condensed (LC) phase were formed on the DMSO-containing subphase at the mean molecular area where only gaseous and LE phases were previously observed on the pure water subphase. These results clearly demonstrate the condensing and caging effect of DMSO molecules on the DPPC monolayer. Similar effects were found on dipalmitoyl phosphatidyl ethanolamine, glycerol, and serine phospholipids, indicating that the condensing and caging effect is not dependent upon the phospholipid headgroup structure. The DMSO-induced condensing and caging effect is the molecular mechanism that may account for the enhanced permeability of membranes upon exposure to DMSO.
2. The Synthesis and Photophysical Properties of Weakly Coupled Diketopyrrolopyrroles
Beata Koszarna,John A Clark,James B Derr,Valentine I Vullev,Michał Pieczykolan,Olena Vakuliuk,Daniel T Gryko,Amara Chrayteh,Denis Jacquemin Molecules . 2021 Aug 5;26(16):4744. doi: 10.3390/molecules26164744.
Three centrosymmetric diketopyrrolopyrroles possessing either two 2-(2'-methoxyphenyl)benzothiazole or two 2-(2'-methoxyphenyl)benzoxazolo-thiophene scaffolds were synthesized in a straightforward manner, and their photophysical properties were investigated. Their emission was significantly bathochromically shifted as compared with that of simple DPPs reaching 650 nm. Judging from theoretical calculations performed with time-dependent density functional theory, in all three cases the excited state was localized on the DPP core and there was no significant CT character. Consequently, emission was almost independent of solvents' polarity. DPPs possessing 2,5-thiophene units vicinal to DPP core play a role in electronic transitions, resulting in bathochromically shifted absorption and emission. Interestingly, as judged from transient absorption dynamics, intersystem crossing was responsible for the deactivation of the excited states of DPPs possessingparalinkers but not in the case of dye bearingmetalinker.
3. Pathophysiological Implications of Dipeptidyl Peptidases
Akira Sato,Hisakazu Ogita Curr Protein Pept Sci . 2017;18(8):843-849. doi: 10.2174/1389203718666170329104936.
Dipeptidyl peptidases (DPPs) belong to one of the protease families classified under EC 3.4.14 in the Nomenclature Committee of the International Union of Biochemistry and Molecular Biology. DPPs family consists of eight members in the mammalian species. They play a role in oligopeptide N-terminal processing and degradation of bioactive peptides. Over the past 20 years, most of the studies have been focused on DPP 4 that has important roles in metabolism and immunity. A large number of pharmacological inhibitors against DPP 4 have been tested rigorously and some of them are now used in the treatment of type 2 diabetes and obesity. In addition, current researches cast a spotlight on other physiological and pathological functions of DPP family members such as DPP 3 for the purpose of investigating their application as novel therapeutic compounds. In this review, we provide an update about the pathophysiological functions of DPPs, and discuss the future potential of the DPP family as pharmacological and therapeutic agents and targets.
4. Study of the effect of Na+ and Ca2+ ion concentration on the structure of an asymmetric DPPC/DPPC + DPPS lipid bilayer by molecular dynamics simulation
Rodolfo D Porasso,J J López Cascales Colloids Surf B Biointerfaces . 2009 Oct 1;73(1):42-50. doi: 10.1016/j.colsurfb.2009.04.028.
A molecular dynamics simulation study of the steady and dynamic properties of an asymmetric phospholipid bilayer was carried out in the presence of sodium or calcium ions. The asymmetric lipid bilayer was seen to resemble a cellular membrane of an eukaryotic cell, which was modeled by dipalmitoylphosphatidylcholine (DPPC) and dipalmitoylphosphatidylserine (DPPS), placing the DPPS in one of the two leaflets of the lipid bilayer. From a numerical analysis of the simulated trajectories, information was obtained with atomic resolution for both membrane leaflet concerning the effect of bilayer asymmetry on different properties of the lipid/water interface, such as the translational diffusion coefficient and rotational relaxation time of the water molecules, lipid hydration, and residence time of water around different lipid atoms. In addition, information related to lipid conformation, and lipid-lipid interactions was also analyzed.
