scholarly journals Ảnh hưởng của nhiệt độ sấy đến hàm lượng hợp chất polyphenol, sắc tố carotenoids, chlorophyll và hoạt tính chống oxy hóa của cây rau càng cua (Peperomia pellucida L.) thu ở tỉnh Tiền Giang

2021 ◽  
Vol 16 (1) ◽  
pp. 25-33
Author(s):  
Trương Quốc Tất ◽  
Phùng Thị Thúy Liễu ◽  
Nguyễn Thị Phương Trang ◽  
Nguyễn Duy Khánh
Keyword(s):  
Chlorophyll A

Mục tiêu của nghiên cứu này là đánh giá sự ảnh hưởng của nhiệt độ sấy đến hàm lượng của các hợp chất có giá trị sinh học trong cây rau càng cua (Peperomia pellucida L.) và hoạt tính chống oxy hóa của dịch trích của nó. Cây rau càng cua được sấy ở các mức nhiệt độ 50, 60, 70 và 80ºC đến độ ẩm đạt ≤ 10%, sau đó rau càng cua khô được nghiền và rây để thu bột mịn. Bột rau càng cua được trích ly bằng ethanol 70%, thu dịch và tiến hành phân tích các chỉ tiêu polyphenol tổng số (TPP), sắc tố carotenoids, chlorophyll và phần trăm gốc tự do DPPH bị khử. Kết quả nghiên cứu khi sấy rau càng cua ở nhiệt độ 50 - 80ºC, hàm lượng TPP dao động trong khoảng 6.65 - 12.88 (mgGAE/g DM), carotenoids dao động trong khoảng 96.88 - 132.78 (µg/g DM), chlorophyll a và b lần lượt dao động trong khoảng 800.5 – 1,205.60 (µg/g DM) và 560.94 - 665.40 (µg/g DM) và phần trăm khử gốc tự do DPPH dao động trong khoảng 53.73 - 69.54%. Các mẫu rau càng cua được sấy ở nhiệt độ 70ºC giữ lại hàm lượng TPP, khả năng chống oxy hóa tốt hơn và đồng thời giữ lại màu sắc khá tốt so với 3 mẫu còn lại.

High-Resolution electron crystallography of the light-harvesting chlorophyll-a/b protein complex from chloroplast membranes

1990 ◽  
Vol 48 (1) ◽  
pp. 610-610
Author(s):  
Werner Kühlbrandt ◽  
Da Neng Wang ◽  
K.H. Downing
Keyword(s):  
High Resolution ◽  
Electron Diffraction ◽  
Chlorophyll A ◽  
Protein Complex ◽  
Structural Integrity ◽  
Light Harvesting ◽  
Lhc Ii ◽  
Diffraction Patterns ◽  
Difference Fourier ◽  
2D Crystals

The light-harvesting chlorophyll-a/b protein complex (LHC-II) is the most abundant membrane protein in the chloroplasts of green plants where it functions as a molecular antenna of solar energy for photosynthesis. We have grown two-dimensional (2d) crystals of the purified, detergent-solubilized LHC-II . The crystals which measured 5 to 10 μm in diameter were stabilized for electron microscopy by washing with a 0.5% solution of tannin. Electron diffraction patterns of untilted 2d crystals cooled to 130 K showed sharp spots to 3.1 Å resolution. Spot-scan images of 2d crystals were recorded at 160 K with the Berkeley microscope . Images of untilted crystals were processed, using the unbending procedure by Henderson et al . A projection map of the complex at 3.7Å resolution was generated from electron diffraction amplitudes and high-resolution phases obtained by image processing .A difference Fourier analysis with the same image phases and electron diffraction amplitudes recorded of frozen, hydrated specimens showed no significant differences in the 3.7Å projection map. Our tannin treatment therefore does not affect the structural integrity of the complex.

Identification of a single-copy gene encoding a Type I chlorophyll a/b-binding polypeptide of photosystem I in Arabidopsis thaliana

1992 ◽  
Vol 84 (4) ◽  
pp. 561-567 ◽  
Author(s):  
Poul E. Jensen ◽  
Michael Kristensen ◽  
Tine Hoff ◽  
Jan Lehmbeck ◽  
Bjarne M. Stummann ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Chlorophyll A ◽  
Photosystem I ◽  
Single Copy ◽  
Type I ◽  
Single Copy Gene ◽  
Gene Encoding ◽  
Copy Gene

Phytoplankton communities and size-fractioned chlorophyll a in newly opened summer waters of the central Arctic Ocean

2019 ◽  
Vol 622 ◽  
pp. 67-82
Author(s):  
Y Wang ◽  
Jh Kang ◽  
P Xiang ◽  
Yy Ye ◽  
Hs Lin ◽  
...  
Keyword(s):  
Arctic Ocean ◽  
Chlorophyll A ◽  
Central Arctic Ocean ◽  
Phytoplankton Communities

Modeling of photosynthesis light curves by linear splines

2019 ◽  
pp. 20-29
Author(s):  
Alexander S. Lelekov ◽  
Rudolf P. Trenkenshu
Keyword(s):  
Experimental Data ◽  
Chlorophyll A ◽  
Skeletonema Costatum ◽  
Light Flux ◽  
Photosynthesis Rate ◽  
Light Curves ◽  
External Irradiation ◽  
Exchange Reactions ◽  
Cell Adaptation ◽  
Linear Splines

The paper presents an example of the linear splines use to describe the photosynthesis light curves for microalgae culture. The main mathematical models of the relationship between photosynthesis rate and light are listed. Based on the previously formulated basic principles of modeling microalgae photobiosynthesis, a mathematical model is proposed that describes the dependence of the assimilation number of chlorophyll a on the value of the light flux by linear splines. The advantage of the proposed approach is a clear definition of the point of change of the limiting factor. It is shown that light-limited photosynthesis rate is determined not only by external irradiation, but also by the concentration of chlorophyll a. The light-saturated rate depends on the amount of a key enzyme complex, which limits the rate of energy exchange reactions in the cell. Verification of the proposed model on the example of the diatom microalgae Skeletonema costatum was carried out. It is shown that the higher the degree of cell adaptation to high irradiation, the better the photosynthesis curve is described by linear splines. If S. costatum cells are adapted to low irradiation, deviations of experimental data from the idealized broken line are observed, which are caused by changes in the pigment composition. When the experimental data are normalized, the cell adaptation factor is reduced, all points are described by a single broken line, which indicates the universality of the proposed approach.

Estimation of chlorophyll content by absorption spectra of native Spirulina platensis cells

2020 ◽  
pp. 25-33
Author(s):  
Leonid E. Paramonov
Keyword(s):  
Chlorophyll Content ◽  
Chlorophyll A ◽  
Absorption Spectra ◽  
Spirulina Platensis ◽  
Intracellular Concentration ◽  
Absorption Coefficients

A method for retrieving the absorption coefficients of Spirulina platensis pigments using absorption spectra of native cells and excluding the use of extracts is considered. Estimates of the intracellular concentration of chlorophyll a, С-phycoerythrin, С- phycocyanin and allophycocyanin in native cells are discussed.

Dynamics of Chlorophyll a Content Depending on Phytoplankton Structure (on the Example of the Teterev River)

2006 ◽  
Vol 42 (6) ◽  
pp. 35-46
Author(s):  
V. I. Shcherbak ◽  
L. A. Sirenko ◽  
Yu. S. Kuzminchuk
Keyword(s):  
Chlorophyll A ◽  
Phytoplankton Structure ◽  
Chlorophyll A Content
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