: This study aimed to isolate and characterize sulfated polysaccharides (SPs) from Iridaea cordata and evaluate their anticancer activity. SPs of the Antarctic red seaweed were obtained by CaCl 2 (SP1) and ethanol precipitations (SP2) following diluted acid extraction at room temperature. Yields of SP1 and SP2 were approximately 14% and 23%, respectively, of the dry weight of red seaweed. The average molecular mass of the SP1 and SP2 was estimated about 1.84 × 10 3 and 1.42 × 10 3 kDa, respectively, by size-fractionation High-Performance Liquid Chromatography (HPLC). From the High-Performance AnionExchange Chromatography-Pulsed Amperometric Detection (HPAEC-PAD) analysis, the main monosaccharide was galactose with glucose and fucose as minor components. The sulfate content of SP2 (40.4%) was slightly higher than that of SP1 (33.8%). The FT-IR spectra also showed characteristic band of carrageenan-like sulfated polysaccharides. Taken together the SPs are thought to be carrageenan-like sulfated galactan. The polysaccharides (SPs) from I. cordata exhibited weak antitumor activity against PC-3 (prostate cancer), HeLa (cervical cancer), and HT-29 (human colon adenocarcinoma). To our knowledge, this is the first data on biological activity of the Antarctic red seaweed I. cordata.
Penelitian ini bertujuan untuk mengetahui pengaruh bentuk kampuh terhadap cacat dan kekuatantarik material baja karbon rendah hasil pengelasan SMAW dengan elektroda AWS E. 7018. Jenis kampuh lasyang digunakan adalah kampuh V dan X, penyiapan bahan dengan menggunakan mesin scrap. Variasi arusyang digunakan adalah 140, 150, 160 dan 170 A dengan polaritas DC +.Proses pengelasan dilakukan di laboratorium las Teknik Mesin Universitas Negeri Jakarta,kemudian proses pengujian radiografi di PT. Gamma Hepsi dan proses pengujian tarik dilakukan di B2TKSPuspitek. Dari kedua hasil pengujian tersebut dilakukan analisa supaya didapatkan kesimpulan.Kesimpulan yang dapat ditarik dari hasil penelitian ini adalah: Hasil pengelasan SMAW denganarus 140 A, 150 A, 160 A dan 170 A yang menggunakan kampuh X mendapatkan nilai tegangan tarik rataratayang lebih rendah terhadap spesimen yang menggunakan kampuh V dengan selisih tegangan tarik rataratasebesar 35,14 N/mm2. Hal ini terjadi karena pengelasan dengan kampuh X mengalami prosespengelasan di dua sisi pada waktu yang berbeda. Hal ini menyebabkan pada spesimen kampuh X memilikitegangan tarik terendah karena adanya tegangan sisa yang besar.
Most cold-adapted enzymes possess higher K and k values than those of their mesophilic counterparts to maximize the reaction rate. This characteristic is often ascribed to a high structural flexibility and improved dynamics in the active site. However, this may be less convincing to cold-adapted metabolic enzymes, which work at substrate concentrations near K. In this respect, cold adaptation of a shikimate kinase (SK) in the shikimate pathway from psychrophilic (CpSK) was characterized by comparing it with a mesophilic homolog (EcSK). The optimum temperatures for CpSK and EcSK activity were approximately 30°C and 40°C, respectively. The melting points were 33°C and 45°C for CpSK and EcSK, respectively. The ΔG (denaturation in the absence of denaturing agent) values were 3.94 and 5.74 kcal/mol for CpSK and EcSK, respectively. These results indicated that CpSK was a cold-adapted enzyme. However, contrary to typical kinetic data, CpSK had a lower K for its substrate shikimate than most mesophilic SKs, and the k was not increased. This observation suggested that CpSK may have evolved to exhibit increased substrate affinity at low intracellular concentrations of shikimate in the cold environment. Sequence analysis and homology modeling also showed that some important salt bridges were lost in CpSK, and higher Arg residues around critical Arg 140 seemed to increase flexibility for catalysis. Taken together, these data demonstrate that CpSK exhibits characteristics of cold adaptation with unusual kinetic parameters, which may provide important insights into the cold adaptation of metabolic enzymes.
Telah dilakukan penelitian mengenai pengaruh temperatur kalsinasi pada modifikasi lempung dengan oksida aluminium sebagai pemilar menggunakan metode pilarisasi tak langsung. Hasil XRD menunjukkan bahwa jenis lempung yang digunakan adalah Ca-montmorilonit (Ca-MMT). Modifikasi montmorilonit menggunakan surfaktan CTAB berhasil dilakukan dengan peningkatan nilai basal spacing d001 sebesar 0,47 nm. Temperatur kalsinasi pada modifikasi montmorilonit dengan oksida aluminium sebagai pemilar di atas 350°C menyebabkan bidang d001 montmorilonit rusak. Produk Al2O3-MMT yang dikalsinasi menggunakan temperatur 350°C memiliki nilai basal spacing d001 sebesar 1,28 nm.
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