Distribution of Various Peptides in Citrus Fruits (Grapefruit, Lemon, and Orange)

Abstract

Tissue- and species-specific peptides of the grapefruit have been investigated by SDS-PAGE and Western blot. Five peptides from the juice and one peptide from the peel were isolated by preparative gel electrophoresis. Polyclonal antibodies were developed against them in mice. It can be established that 82, 63, and 46 kDa peptides occurred exclusively in the samples prepared from the grapefruit and the lemon juice, whereas in the orange juice, only the 82 kDa peptide could be detected. The 31 kDa peptide is characteristic for the peel samples of grapefruit and lemon. The 210 kDa peptide did not show any specificity. A 117 kDa peptide appeared in the juice and peel of grapefruit and in the peel of lemon but not in the orange. From the data of this study, it is supposed that some of the polyclonal antibodies developed against characteristic juice and peel peptides can be used to test commercial grapefruit juice products for adulteration.

Characterization of blond and Star Ruby (red) Jaffa grapefruits using antioxidant and electrophoretic methods

“…In the present report the proteins were preliminary not precipitated, but the method was modified using different gel concentrations. The presence of four more characteristic proteins (85, 67, 50 and 35 kDa) was detected in the juice in the present study in comparison with Sass‐Kiss & Sass (2002). According to Sass‐Kiss & Sass (2002) another four bands of 65, 46, 82 and 117 kDa were characteristic for grapefruit juices.…”

“…The presence of four more characteristic proteins (85, 67, 50 and 35 kDa) was detected in the juice in the present study in comparison with Sass‐Kiss & Sass (2002). According to Sass‐Kiss & Sass (2002) another four bands of 65, 46, 82 and 117 kDa were characteristic for grapefruit juices. The antibody of the 82 kDa peptide gave a single positive band with the proteins prepared from commercial grapefruit juice products according to Sass‐Kiss & Sass (2002), which is shown in the present report as well.…”

“…Resolution of the bands was satisfactory in the molecular weight region (>36 kDa), but poor in the low molecular weight region (<20 kDa). Nevertheless, we detected more bands in the <28 kDa zone than Sass‐Kiss & Sass, 2000, 2002. The use of a longer gel (14 cm instead of 7 cm) gave more distinct and sharp bands, especially in the >36 kDa zone.…”

“…Entirely new possibilities appeared with the development of electrophoretic techniques (Firon et al. , 1979; Sass‐Kiss & Sass, 2000, 2002). As mentioned, interest in the characterization of citrus fruits is growing, however investigations of the cultivars of the same citrus fruits are practically non‐existent (Gorinstein et al.…”

A peach (Prunus persica)-specific gene, Lhcb2, used as an endogenous reference gene for qualitative and real-time quantitative PCR to detect fruit products

“…Specifically, rapid PCR-based methods with high sensitivity and reproducibility (Lockley & Bardsley, 2000;Mafra, Ferreira, & Oliveira, 2008) have become especially common, for example, in the identification of genetically modified food (Wurz, Bluth, Zeltz, Pfeifer, & Willmund, 1999), meat (Kung et al, 2010), milk and cheese (Sachinandan et al, 2011) and their by-products. Sass-Kiss (Sass-Kiss & Sass, 2002) isolated four tissue-specific peptides from grapefruit juice and peel and successfully tested commercial grapefruit juice products for adulteration. Ng, Chang, Wu, Kotwal, and Shyu (2006) designed primers based on the 18S and internal transcribed spacer (ITS) region of the orange as part of a rapid and accurate molecular approach to identify freshly squeezed and reconstituted orange juice.…”