References: Lecithin
Yao Xue Xue Bao. 2003 Aug;38(8):624-6.
[Preparation of solid lipid nanoparticles by microemulsion technique]
[Article in Chinese]
Mao SR, Wang YZ, Ji HY, Bi DZ.
School of Pharmacy, Shenyang Pharmaceutical University, Shenyang 110016, China.
AIM: To prepare solid lipid nanoparticles by microemulsion technique. METHODS: Stearic acid was used as the oil phase, lecithin as surfactant, alcohol as cosurfactant and distilled water as the aqueous phase. Microemulsion was prepared by mixing the above component in proper ratio. The corresponding pseudoternary phase diagram monitored Microemulsion formation field of different lecithin/alcohol. Solid lipid nanoparticles (SLN) were prepared by dispersing warm microemulsion in cold water under magnetic stirring. Then appropriate microemulsions that can contain more water phase and suitable oil phase were selected to prepare SLN. The influence of formulation, process variables on the preparation and quality of SLN were studied. Based on the investigation of single factors, orthogonal design was used to optimize SLN formulation and preparation process, and more, the reproducibility of the optimized results were studied. RESULTS: The results showed that the device temperature (Ti), water temperature (Tw), and delivery rate (Rd) were the key factors that influence the preparation process of SLN, and Tw was extremely important. The ratio of microemulsion formulation, the ratio of microemulsion and distilled water had also influence on its quality. CONCLUSION: Microemulsion technique can be used to prepare solid lipid nanoparticles.
Laxative online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=14628457&dopt=Abstract lecithin [PubMed - in process]
Braz J Med Biol Res. 1993 Feb;26(2):163-6. ["Protein","window.top.location='Laxative online source: www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?db=PubMed&cmd=Display&dopt=pubmed_protein&from_uid=8257916'","",""],
Purification, physicochemical characterization and N-terminal-amino acid sequence of a phospholipase A2 from Bothrops jararaca venom.
Machado OL, Oliveira-Carvalho AL, Zingali RB, Carlini CR.
Departamento de Bioquimica Medica, Centro de Ciencias da Saude, Rio de Janeiro, Brasil.
Snake venoms usually contain multiple molecular forms of phospholipase A2 enzymes (phosphatide acyl hydrolase, E.C. 3.1.1.4; PLA2). Phospholipases A2 induce a wide range of pharmacological effects which may depend or not on the hydrolysis of phospholipids. In this study, a PLA2 from Bothrops jararaca venom was purified to homogeneity by gel filtration on a Sephacryl S-200 column, followed by FPLC reverse-phase chromatography on a Pep-RPC HR 5/5 column (yield 1.63% of venom protein). The PLA2 activity of the fractions was determined by indirect hemolysis using hen's egg yolk lecithin as substrate. The enzyme is an acidic protein with PI 4.5 and an apparent molecular weight of 14,200, as estimated by gel filtration on a Superose 12 FPLC column. Similar properties have been described for PLA2 from other snake venoms. The N-terminal-sequence of the purified protein was NLMQFETMIMXXAGQ. These partial sequence data show a high degree of homology between the B. jararaca PLA2 and the enzymes from other snake venoms as well as bovine pancreatic PLA2.
Laxative online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8257916&dopt=Abstract lecithin
Biochemistry. 2003 Dec 2;42(47):13941-9.
Negative charge at amino acid 149 is the molecular determinant for substrate specificity of lecithin: cholesterol acyltransferase for phosphatidylcholine containing 20-carbon sn-2 fatty acyl chains.
Zhao Y, Wang J, Gebre AK, Chisholm JW, Parks JS.
Department of Pathology, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, North Carolina 27157, USA.
We previously described a point mutation in human LCAT (E to A at residue 149; hE149A) that demonstrated greater activity with phosphatidylcholine (PC) substrate containing 20:4 in the sn-2 position compared with the wild-type enzyme [hLCAT; Wang et al. (1997) J. Biol. Chem. 272, 280-286], resulting in a human enzyme with the substrate specificity similar to that of rat LCAT. The purpose of the present study was to explore the molecular basis for the role of amino acid 149 in determining fatty acyl substrate specificity. In the first experiment, the reverse mutation in rat LCAT (rA149E) converted substrate specificity of rat LCAT toward that of the human enzyme, demonstrating that the mutation was context independent and reversible. In the second experiment, we found that hE149A compared with hLCAT demonstrated higher activity with PC species containing 20-carbon, but not 18-carbon, sn-2 fatty acyl chains. The increased activity of hE149A was due to an increase in apparent V(max) but not to apparent K(m) or LCAT binding to the PC surface. Substitution of different amino acids in the 149 position of hLCAT showed that activation of the enzyme with sn-2 20:4 containing PC substrate was only observed when the negative charge at residue 149 was removed. We conclude that the negative charge at amino acid 149 of LCAT is a critical determinant for the specificity of the enzyme for PC containing 18- vs 20-carbon sn-2 fatty acyl chains.
Laxative online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=14636062&dopt=Abstract lecithin
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