Insights into the infrared and Raman spectra of fresh and lyophilized royal jelly and protein degradation IR spectroscopy study during heating

Abstract

In terms of chemical composition, a honeybee secretion known as royal jelly (RJ) is very complex product containing water, proteins, carbohydrates, lipids, mineral salts and small amounts of polyphenols, vitamins and enzymes. Despite its chemical diversity, the bands originating from vibrational modes of the present proteins were successfully assigned in 1800-1200 cm -1 (Raman and IR) region where the interference of bands from other vibrational species is not substantial. The protein bands were attributed to amide I, amide II and amide III modes and their intensities, additionally, enabled to determine the protein secondary structures. The remaining bands up to 4000 cm -1 were attributed to other group vibrations whereas the region below 1200 cm -1 comprises bands from complex interacting modes within the major RJ components that can not be unequivocally attributed to distinct modes. The work also represents a pioneering effort to collect and interpret the Raman spectrum of fresh and lyophilized RJ samples and to correlate and describe the observed similarities/differences between IR and Raman spectra.Keywords: royal jelly; infrared; Raman spectra; band assignments; protein degradation УВИД ВО ИНФРАЦРВЕНИТЕ И РАМАНСКИТЕ СПЕКТРИ НА СВЕЖ И ЛИОФИЛИЗИРАН МАТИЧЕН МЛЕЧ И СТУДИЈА ЗА ПРОТЕИНСКАТА ДЕГРАДАЦИЈА ПРИ ЗАГРЕВАЊЕ СЛЕДЕНА СО ИНФРАЦРВЕНА СПЕКТРОСКОПИЈАМатичниот млеч (ММ), кој претставува пчелин секрет, има комплексен хемиски состав и содржи: вода, протеини, јаглехидрати, масти, минерални соли и мало количество полифеноли, витамини и ензими. И покрај разновидноста во хемискиот состав, инфрацрвените и раманските ленти кои потекнуваат од присутните протеини беа успешно асигнирани во подрачјето од 1800 до 1200 cm -1 . Тоа се должи на фактот што во оваа област интерференцијата, изразена преку преклопување на ленти од другите хемиски ентитети, е незначителна. Протеинските ленти беа припишани на модовите амид I, амид II и амид III, а интензитетите на лентите дополнително овозможија определување на секундарните структури на протеините. Другите спектрални ленти регистрирани до 4000 cm -1 беа асигнирани на други групови вибрации, додека во областа под 1200 cm -1 не може да се направи еднозначна интерпретација на спектрите поради силното преклопување помеѓу вибрационите ленти од многуте пристутни хемиски конституенти во ММ. Оваа студија претставува пионерски обид да се добијат и интерпретираат раманските спектри на свеж и лиофилизиран ММ како и да се корелираат и објаснат детектираните спектрални сличности/разлики помеѓу инфрацрвените и раманските спектри.Клучни зборови: матичен млеч; инфрацрвен; рамански спектар; асигнација на ленти; протеинска деградација  Dedicated to Academician Gligor Jovanovski on the occasion of his 70 th birthday. S. Lazarevska, P. MakreskiMaced. J. Chem. Chem. Eng. 34(1), 87-93 (2015) 88

pH-dependent stability of honey bee (Apis mellifera) major royal jelly proteins

“…The different MRJPs showed at pH 4.0 a remarkable stability with melting temperatures ranging between 59.3 to 64.2 °C. This is in accord with accelerated protein degradation in fresh RJ above 65 °C 46 as the proteins unfold at these temperatures.…”

Current Status of the Bioactive Properties of Royal Jelly: A Comprehensive Review with a Focus on Its Anticancer, Anti-Inflammatory, and Antioxidant Effects

“…The chemical composition of RJ consists of water (60–78%), proteins (9–18%), carbohydrates (7–18%), lipids (3–8%), mineral salts (0.8–3%), small amounts of polyphenols, vitamins, and enzymes [ 25 , 26 ]. In general, RJ is relatively acidic with a high buffering capacity (pH 3.20–4.01) and the total acidity varies between 2.48–4.66 mL 0.1 N NaOH/g [ 27 ].…”

Deciphering the Raman spectrum of royal jelly. Fabrication of Ag‐polymer embedded royal jelly nanoparticles manifesting SERS effect

“…In the AgNP-PEG-RJ spectrum (Figure 3b), the obscured band at 2,968 cm −1 in the raw Raman RJ spectrum (Figure 3a) is attributed to the C-H stretching vibrations within the -CH 2groups in the proteins. [23,24] The assignment of the Raman bands continues in the 1,700 to 1,450 cm −1 region where the bands from the secondary protein structure (α-helices and β-sheets) are evidenced [9] ( Table 2). The α-helix is the more frequent and stable secondary structure of polypeptides and proteins compared with β-sheets.…”

“…The band at 1,267 cm −1 has mixed character of symmetric CH 2 vibrations and C-C-H, O-H-C, and C-O-H bending modes in sugars overlying with the peptide amide III mode. [21] Although the band absorptions below 1,200 cm −1 in RJ are not discussed previously in any literature reports [9] because they correspond to complex interacting vibrational modes within the major components present in the RJ, here, we prescribe dominant presence of the C-O and C-C stretchings as well as C-H, C-C-O, and C-C-C bendings within the monosaccharide and disaccharide units for the bands in the 1,100-500 cm −1 . The band at 1,073 cm −1 originate from the presence of glucose as it appears with a much stronger intensity in glucose with diminishing intensity in fructose.…”

“…To the best of our knowledge, the Raman spectra of RJ have been presented only in our previous work, and in the recent work studying water suspensions of Ag‐based RJ nanostructures, offering a very limited interpretation of the RJ Raman behavior. Here, we intend to extend the band assignments in the whole region by fabrication of RJ‐adsorbed Ag nanoparticles (AgNPs).…”