When papers or articles say that all proteinogenic amino acids are 'levorotatory' or 'L', they often make a point of saying that only half of them are truly, optically levorotatory. All of them (except glycine) are called 'L' because of their 'opposing' configuration to glyceraldehyde, the original molecule deemed to be dextrorotatory...

Well, all sugars used by living things are supposedly 'R', or so I keep reading....

Are they similar in configuration to glyceraldehyde, or actually levorotatory to light?

When papers or articles say that all proteinogenic amino acids are 'levorotatory' or 'L', they often make a point of saying that only half of them are truly, optically levorotatory. All of them (except glycine) are called 'L' because of their 'opposing' configuration to glyceraldehyde, the original molecule deemed to be dextrorotatory...

Well, all sugars used by living things are supposedly 'R', or so I keep reading....

Are they similar in configuration to glyceraldehyde, or actually dextrorotatory to light?

EDIT: What I really wanted to know, in posting this question, is whether less than half, or most, or all organic sugars and carbohydrates are ACTUALLY optically active, in the sense of lowercase d or +,....

Remember, I noted that only 10 of 20 proteinogenic amino acids are actually levorotatory to polarized light....