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Title:	Characterization of functional bioactive peptides from snakehead fish (channa striatus) meat proteins
Authors:	Masomeh Ghassem (P42598)
Supervisor:	Abdul Salam Babiji, Prof. Dr.
Keywords:	Peptides -- Malaysia Northern snakehead -- Malaysia Universiti Kebangsaan Malaysia -- Dissertations Dissertations, Academic -- Malaysia
Issue Date:	5-May-2012
Description:	"Haruan" (Channa striatus) is a freshwater fish popular among post-operative patients to induce wound healing. Hypertension is considered a risk factor for developing cardiovascular diseases and Angiotensin-I converting enzyme (ACE) is involved in increasing blood pressure. This study was conducted to evaluate the kinetics of proteolytic activity of proteinase K and thermolysin on C. striatus muscle proteins and measure the ACE inhibitory activity of the hydrolysates produced. Sarcoplasmic (S) and myofibrillar (M) proteins of C. striatus were hydrolyzed with proteinase K (P) to produce SP and MP, and thermolysin (T) to produce ST and MT separately. Results of this study indicated that after 30 min incubation with proteases, a decrease in degree of hydrolysis (DH) of SP and ST was observed whereas, hydrolysis of MP and MT took 2 h with an increase in DH. The apparent Michaelis constant of proteinase K was lower (SP= 0.96 and MP= 1.87 mg/mL) than thermolysin (ST= 2.79 and MT= 19.68 mg/mL) for both proteins. However, the results on the rate of turnover and enzyme efficiency suggested that sarcoplasmic and myofibrillar proteins were suitable substrates for proteinase K and thermolysin hydrolytic reaction, respectively. ACE inhibitory peptides were isolated from SP and MT of C. striatus. Both protein hydrolysates were fractionated by ultrafiltration, size exclusion chromatography (SEC) and reversed-phased high performance liquid chromatography (RP-HPLC). Four and three fractions were collected from SP and MT, respectively using polyacrylamide Bio-Gel P-2 column. The amino acid compositions of P4 (from SP) and P2 (from MT) with the highest inhibitory activity showed higher amounts of essential and hydrophobic amino acids compared to their hydrolysates. Fraction P4 was separated into seven (A-G) and P2 into five (A-E) potent fractions with RPHPLC. Fractions F (from P4) and C (from P2) with the highest ACE inhibitory activity of 9.37 and 10.32 μg/mL, respectively showed high resistance towards to pH, temperature and gastrointestinal enzymes were collected and their sequences were identified and characterized using HPLC coupled to Electrospray Ionization-micro Quadropole-Time Of Flight- Mass Spectrometer (ESI-MicroQ-TOF-MS). After spectrometric analysis, peptide sequences for the most abundant fragments of fraction F were identified as YSMFPP (IC50=1.8 μM) and YLFLSFWP (IC50=2.2 μm) which both contained Tyr residue at the N-terminal and aromatic and Pro residues at the Cterminal positions, necessary for binding to the active sites of ACE and hence inhibit or lower its activity. The peptide sequences for fraction C were identified as VPAAPPK (IC50 = 0.45 μM) and NGTWFEPP (IC50 = 0.63 μM). Both peptides had two Pro residues at the penultimate position of their C-terminal sequences responsible for their high ACE inhibitory activity. The results of this study presented a new highly ACE inhibitory peptides formed by proteinase K- and thermolysin-catalysed hydrolysis of sarcoplasmic and myofibrillar proteins of haruan fish meat which could be used as functional ingredients for blood pressure reduction.,"Certification of Master's/Doctoral Thesis" is not available,Ph.D.
Pages:	257
Call Number:	QR82.E6G493 2008 tesis
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Science and Technology / Fakulti Sains dan Teknologi

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